signNow Status
Real-time updates of signNow issues and outages
signNow status is Operational
signNow Web
signNow Mobile apps
signNow API
Active Incidents
Some users may experience issues with SMS invite delivery. Additionally, email invites may be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.
Postmortem: ## Summary
Between February 23 and February 28, 2026, changes in Microsoft’s email filtering behavior intermittently affected delivery of some SignNow invite emails sent to Microsoft-hosted email services, including Outlook, Hotmail, Live, and Microsoft 365.
SignNow systems were operating normally during this period. Email messages were successfully transmitted from SignNow infrastructure and accepted by Microsoft servers. However, Microsoft’s filtering systems intermittently prevented some of these messages from reaching recipient inboxes.
Microsoft later confirmed aggressive spam filtering behavior affecting legitimate email traffic from certain senders and applied mitigation while tuning their filtering models.
After confirmation from Microsoft that mitigation had been applied, SignNow proactively re-sent affected unsigned invites and notified impacted document owners.
Email delivery behavior is currently stable and continues to be monitored.
Timeline
February 23, 2026Early signals of email delivery issues begin to appear related to Microsoft-hosted email domains.
February 26, 2026SignNow begins receiving customer reports that some invite emails sent to Microsoft domains are not reaching recipient inboxes.
February 27, 2026Engineering investigation confirms that emails are successfully transmitted from SignNow infrastructure and accepted by Microsoft servers.
SignNow escalates the issue to Microsoft and begins collaborating with affected customers to collect delivery traces.
February 28, 2026Microsoft confirms aggressive spam filtering behavior affecting legitimate emails and applies temporary mitigation.
March 1, 2026Microsoft confirms mitigation has been applied broadly.
March 2, 2026SignNow automatically re-sends affected unsigned invites to ensure recipients receive the documents.
March 4, 2026Targeted communication is sent to document owners whose invites may have been affected.
Root Cause
The incident was caused by Microsoft spam filtering behavior driven by machine-learning detection models that intermittently classified some legitimate emails as suspicious.
Although SignNow messages were successfully transmitted and accepted by Microsoft mail servers, some emails were filtered before reaching recipient inboxes.
A sender header configuration detail may have increased sensitivity to Microsoft filtering behavior for certain messages. This configuration has since been reviewed and adjusted.
Impact
During the affected timeframe:
- Some invite emails sent to Microsoft-hosted domains experienced delivery delays or filtering.
- The issue was intermittent and did not affect all messages.
- A subset of senders who frequently send documents to Microsoft-hosted domains experienced higher likelihood of impact.
SignNow received a limited number of customer reports related to missing invite notifications. Each report represented multiple recipients, meaning the number of impacted recipients was higher than the number of reported cases.
Mitigation and Actions Taken
During the investigation, SignNow took the following steps:
- Investigated email delivery logs and confirmed successful transmission from SignNow infrastructure
- Adjusted email header configuration to reduce filtering sensitivity
- Escalated the issue to Microsoft support
- Collaborated with affected customers to gather delivery traces
- Monitored delivery behavior across Microsoft-hosted domains
- Automatically re-sent affected unsigned invites
- Proactively notified impacted document owners
Current Status
Based on Microsoft confirmation and subsequent delivery validation, the issue is considered resolved.
SignNow continues to monitor delivery performance to ensure consistent email delivery to Microsoft-hosted domains.
Resolved: Between February 26 and February 28, Microsoft filtering behavior caused intermittent delivery issues for email invites sent to Microsoft-hosted domains (Outlook, Hotmail, Live, Microsoft 365).
SignNow systems were operating normally, and messages were successfully transmitted and accepted by Microsoft servers. The disruption occurred within Microsoft’s filtering layer due to aggressive spam detection behavior.
Microsoft has identified the issue and is applying backend mitigation (whitelisting) while continuing to tune their detection models.
While awaiting final confirmation from Microsoft, we are proactively re-sending affected unsigned invites to impacted recipients to ensure successful delivery.
We are continuing to monitor delivery behavior closely and will provide updates if needed.
Microsoft confirmed that fix was aplied globally and invites has to be delivered with no further issues. SignNow team will resend all unsgned invites shortly.
SignNow team has resent all affected emails invites.
Monitoring: We are currently awaiting confirmation from Microsoft that the applied fix has been successful.
Monitoring: This incident was caused by aggressive spam filtering behavior within Microsoft-hosted email environments (Outlook, Hotmail, Live, Microsoft 365).
SignNow systems were functioning correctly and emails were successfully accepted by Microsoft servers (SMTP 250 OK). However, Microsoft’s filtering layer intermittently flagged and quarantined certain messages before reaching recipient inboxes.
Microsoft has acknowledged the filtering behavior and applied backend whitelisting for signnow.com as an interim mitigation while tuning their detection models.
The issue is currently mitigated and under monitoring.
Identified: We are still investigating intermittent email delivery issues affecting recipients on Microsoft-hosted domains (including Outlook.com, Hotmail.com, Live.com, and Microsoft 365/Exchange Online environments).
Some emails sent from SignNow to Microsoft-hosted mailboxes are being accepted by Microsoft servers but may not reach the recipient’s inbox. In certain cases, messages may be silently filtered or quarantined.
Identified: The issue has been identified and a fix is being implemented.
Investigating: Issue with sms invites is now being fixed. Email invites still might be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.
Investigating: Some users may experience issues with SMS invite delivery. Additionally, email invites may be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.
Recently Resolved Incidents
No recent incidents
signNow Outage Survival Guide
signNow Components
signNow Web
Some users may experience issues with SMS invite delivery. Additionally, email invites may be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.
Postmortem: ## Summary
Between February 23 and February 28, 2026, changes in Microsoft’s email filtering behavior intermittently affected delivery of some SignNow invite emails sent to Microsoft-hosted email services, including Outlook, Hotmail, Live, and Microsoft 365.
SignNow systems were operating normally during this period. Email messages were successfully transmitted from SignNow infrastructure and accepted by Microsoft servers. However, Microsoft’s filtering systems intermittently prevented some of these messages from reaching recipient inboxes.
Microsoft later confirmed aggressive spam filtering behavior affecting legitimate email traffic from certain senders and applied mitigation while tuning their filtering models.
After confirmation from Microsoft that mitigation had been applied, SignNow proactively re-sent affected unsigned invites and notified impacted document owners.
Email delivery behavior is currently stable and continues to be monitored.
Timeline
February 23, 2026Early signals of email delivery issues begin to appear related to Microsoft-hosted email domains.
February 26, 2026SignNow begins receiving customer reports that some invite emails sent to Microsoft domains are not reaching recipient inboxes.
February 27, 2026Engineering investigation confirms that emails are successfully transmitted from SignNow infrastructure and accepted by Microsoft servers.
SignNow escalates the issue to Microsoft and begins collaborating with affected customers to collect delivery traces.
February 28, 2026Microsoft confirms aggressive spam filtering behavior affecting legitimate emails and applies temporary mitigation.
March 1, 2026Microsoft confirms mitigation has been applied broadly.
March 2, 2026SignNow automatically re-sends affected unsigned invites to ensure recipients receive the documents.
March 4, 2026Targeted communication is sent to document owners whose invites may have been affected.
Root Cause
The incident was caused by Microsoft spam filtering behavior driven by machine-learning detection models that intermittently classified some legitimate emails as suspicious.
Although SignNow messages were successfully transmitted and accepted by Microsoft mail servers, some emails were filtered before reaching recipient inboxes.
A sender header configuration detail may have increased sensitivity to Microsoft filtering behavior for certain messages. This configuration has since been reviewed and adjusted.
Impact
During the affected timeframe:
- Some invite emails sent to Microsoft-hosted domains experienced delivery delays or filtering.
- The issue was intermittent and did not affect all messages.
- A subset of senders who frequently send documents to Microsoft-hosted domains experienced higher likelihood of impact.
SignNow received a limited number of customer reports related to missing invite notifications. Each report represented multiple recipients, meaning the number of impacted recipients was higher than the number of reported cases.
Mitigation and Actions Taken
During the investigation, SignNow took the following steps:
- Investigated email delivery logs and confirmed successful transmission from SignNow infrastructure
- Adjusted email header configuration to reduce filtering sensitivity
- Escalated the issue to Microsoft support
- Collaborated with affected customers to gather delivery traces
- Monitored delivery behavior across Microsoft-hosted domains
- Automatically re-sent affected unsigned invites
- Proactively notified impacted document owners
Current Status
Based on Microsoft confirmation and subsequent delivery validation, the issue is considered resolved.
SignNow continues to monitor delivery performance to ensure consistent email delivery to Microsoft-hosted domains.
Resolved: Between February 26 and February 28, Microsoft filtering behavior caused intermittent delivery issues for email invites sent to Microsoft-hosted domains (Outlook, Hotmail, Live, Microsoft 365).
SignNow systems were operating normally, and messages were successfully transmitted and accepted by Microsoft servers. The disruption occurred within Microsoft’s filtering layer due to aggressive spam detection behavior.
Microsoft has identified the issue and is applying backend mitigation (whitelisting) while continuing to tune their detection models.
While awaiting final confirmation from Microsoft, we are proactively re-sending affected unsigned invites to impacted recipients to ensure successful delivery.
We are continuing to monitor delivery behavior closely and will provide updates if needed.
Microsoft confirmed that fix was aplied globally and invites has to be delivered with no further issues. SignNow team will resend all unsgned invites shortly.
SignNow team has resent all affected emails invites.
Monitoring: We are currently awaiting confirmation from Microsoft that the applied fix has been successful.
Monitoring: This incident was caused by aggressive spam filtering behavior within Microsoft-hosted email environments (Outlook, Hotmail, Live, Microsoft 365).
SignNow systems were functioning correctly and emails were successfully accepted by Microsoft servers (SMTP 250 OK). However, Microsoft’s filtering layer intermittently flagged and quarantined certain messages before reaching recipient inboxes.
Microsoft has acknowledged the filtering behavior and applied backend whitelisting for signnow.com as an interim mitigation while tuning their detection models.
The issue is currently mitigated and under monitoring.
Identified: We are still investigating intermittent email delivery issues affecting recipients on Microsoft-hosted domains (including Outlook.com, Hotmail.com, Live.com, and Microsoft 365/Exchange Online environments).
Some emails sent from SignNow to Microsoft-hosted mailboxes are being accepted by Microsoft servers but may not reach the recipient’s inbox. In certain cases, messages may be silently filtered or quarantined.
Identified: The issue has been identified and a fix is being implemented.
Investigating: Issue with sms invites is now being fixed. Email invites still might be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.
Investigating: Some users may experience issues with SMS invite delivery. Additionally, email invites may be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.
signNow Mobile apps
Some users may experience issues with SMS invite delivery. Additionally, email invites may be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.
Postmortem: ## Summary
Between February 23 and February 28, 2026, changes in Microsoft’s email filtering behavior intermittently affected delivery of some SignNow invite emails sent to Microsoft-hosted email services, including Outlook, Hotmail, Live, and Microsoft 365.
SignNow systems were operating normally during this period. Email messages were successfully transmitted from SignNow infrastructure and accepted by Microsoft servers. However, Microsoft’s filtering systems intermittently prevented some of these messages from reaching recipient inboxes.
Microsoft later confirmed aggressive spam filtering behavior affecting legitimate email traffic from certain senders and applied mitigation while tuning their filtering models.
After confirmation from Microsoft that mitigation had been applied, SignNow proactively re-sent affected unsigned invites and notified impacted document owners.
Email delivery behavior is currently stable and continues to be monitored.
Timeline
February 23, 2026Early signals of email delivery issues begin to appear related to Microsoft-hosted email domains.
February 26, 2026SignNow begins receiving customer reports that some invite emails sent to Microsoft domains are not reaching recipient inboxes.
February 27, 2026Engineering investigation confirms that emails are successfully transmitted from SignNow infrastructure and accepted by Microsoft servers.
SignNow escalates the issue to Microsoft and begins collaborating with affected customers to collect delivery traces.
February 28, 2026Microsoft confirms aggressive spam filtering behavior affecting legitimate emails and applies temporary mitigation.
March 1, 2026Microsoft confirms mitigation has been applied broadly.
March 2, 2026SignNow automatically re-sends affected unsigned invites to ensure recipients receive the documents.
March 4, 2026Targeted communication is sent to document owners whose invites may have been affected.
Root Cause
The incident was caused by Microsoft spam filtering behavior driven by machine-learning detection models that intermittently classified some legitimate emails as suspicious.
Although SignNow messages were successfully transmitted and accepted by Microsoft mail servers, some emails were filtered before reaching recipient inboxes.
A sender header configuration detail may have increased sensitivity to Microsoft filtering behavior for certain messages. This configuration has since been reviewed and adjusted.
Impact
During the affected timeframe:
- Some invite emails sent to Microsoft-hosted domains experienced delivery delays or filtering.
- The issue was intermittent and did not affect all messages.
- A subset of senders who frequently send documents to Microsoft-hosted domains experienced higher likelihood of impact.
SignNow received a limited number of customer reports related to missing invite notifications. Each report represented multiple recipients, meaning the number of impacted recipients was higher than the number of reported cases.
Mitigation and Actions Taken
During the investigation, SignNow took the following steps:
- Investigated email delivery logs and confirmed successful transmission from SignNow infrastructure
- Adjusted email header configuration to reduce filtering sensitivity
- Escalated the issue to Microsoft support
- Collaborated with affected customers to gather delivery traces
- Monitored delivery behavior across Microsoft-hosted domains
- Automatically re-sent affected unsigned invites
- Proactively notified impacted document owners
Current Status
Based on Microsoft confirmation and subsequent delivery validation, the issue is considered resolved.
SignNow continues to monitor delivery performance to ensure consistent email delivery to Microsoft-hosted domains.
Resolved: Between February 26 and February 28, Microsoft filtering behavior caused intermittent delivery issues for email invites sent to Microsoft-hosted domains (Outlook, Hotmail, Live, Microsoft 365).
SignNow systems were operating normally, and messages were successfully transmitted and accepted by Microsoft servers. The disruption occurred within Microsoft’s filtering layer due to aggressive spam detection behavior.
Microsoft has identified the issue and is applying backend mitigation (whitelisting) while continuing to tune their detection models.
While awaiting final confirmation from Microsoft, we are proactively re-sending affected unsigned invites to impacted recipients to ensure successful delivery.
We are continuing to monitor delivery behavior closely and will provide updates if needed.
Microsoft confirmed that fix was aplied globally and invites has to be delivered with no further issues. SignNow team will resend all unsgned invites shortly.
SignNow team has resent all affected emails invites.
Monitoring: We are currently awaiting confirmation from Microsoft that the applied fix has been successful.
Monitoring: This incident was caused by aggressive spam filtering behavior within Microsoft-hosted email environments (Outlook, Hotmail, Live, Microsoft 365).
SignNow systems were functioning correctly and emails were successfully accepted by Microsoft servers (SMTP 250 OK). However, Microsoft’s filtering layer intermittently flagged and quarantined certain messages before reaching recipient inboxes.
Microsoft has acknowledged the filtering behavior and applied backend whitelisting for signnow.com as an interim mitigation while tuning their detection models.
The issue is currently mitigated and under monitoring.
Identified: We are still investigating intermittent email delivery issues affecting recipients on Microsoft-hosted domains (including Outlook.com, Hotmail.com, Live.com, and Microsoft 365/Exchange Online environments).
Some emails sent from SignNow to Microsoft-hosted mailboxes are being accepted by Microsoft servers but may not reach the recipient’s inbox. In certain cases, messages may be silently filtered or quarantined.
Identified: The issue has been identified and a fix is being implemented.
Investigating: Issue with sms invites is now being fixed. Email invites still might be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.
Investigating: Some users may experience issues with SMS invite delivery. Additionally, email invites may be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.
signNow API
Some users may experience issues with SMS invite delivery. Additionally, email invites may be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.
Postmortem: ## Summary
Between February 23 and February 28, 2026, changes in Microsoft’s email filtering behavior intermittently affected delivery of some SignNow invite emails sent to Microsoft-hosted email services, including Outlook, Hotmail, Live, and Microsoft 365.
SignNow systems were operating normally during this period. Email messages were successfully transmitted from SignNow infrastructure and accepted by Microsoft servers. However, Microsoft’s filtering systems intermittently prevented some of these messages from reaching recipient inboxes.
Microsoft later confirmed aggressive spam filtering behavior affecting legitimate email traffic from certain senders and applied mitigation while tuning their filtering models.
After confirmation from Microsoft that mitigation had been applied, SignNow proactively re-sent affected unsigned invites and notified impacted document owners.
Email delivery behavior is currently stable and continues to be monitored.
Timeline
February 23, 2026Early signals of email delivery issues begin to appear related to Microsoft-hosted email domains.
February 26, 2026SignNow begins receiving customer reports that some invite emails sent to Microsoft domains are not reaching recipient inboxes.
February 27, 2026Engineering investigation confirms that emails are successfully transmitted from SignNow infrastructure and accepted by Microsoft servers.
SignNow escalates the issue to Microsoft and begins collaborating with affected customers to collect delivery traces.
February 28, 2026Microsoft confirms aggressive spam filtering behavior affecting legitimate emails and applies temporary mitigation.
March 1, 2026Microsoft confirms mitigation has been applied broadly.
March 2, 2026SignNow automatically re-sends affected unsigned invites to ensure recipients receive the documents.
March 4, 2026Targeted communication is sent to document owners whose invites may have been affected.
Root Cause
The incident was caused by Microsoft spam filtering behavior driven by machine-learning detection models that intermittently classified some legitimate emails as suspicious.
Although SignNow messages were successfully transmitted and accepted by Microsoft mail servers, some emails were filtered before reaching recipient inboxes.
A sender header configuration detail may have increased sensitivity to Microsoft filtering behavior for certain messages. This configuration has since been reviewed and adjusted.
Impact
During the affected timeframe:
- Some invite emails sent to Microsoft-hosted domains experienced delivery delays or filtering.
- The issue was intermittent and did not affect all messages.
- A subset of senders who frequently send documents to Microsoft-hosted domains experienced higher likelihood of impact.
SignNow received a limited number of customer reports related to missing invite notifications. Each report represented multiple recipients, meaning the number of impacted recipients was higher than the number of reported cases.
Mitigation and Actions Taken
During the investigation, SignNow took the following steps:
- Investigated email delivery logs and confirmed successful transmission from SignNow infrastructure
- Adjusted email header configuration to reduce filtering sensitivity
- Escalated the issue to Microsoft support
- Collaborated with affected customers to gather delivery traces
- Monitored delivery behavior across Microsoft-hosted domains
- Automatically re-sent affected unsigned invites
- Proactively notified impacted document owners
Current Status
Based on Microsoft confirmation and subsequent delivery validation, the issue is considered resolved.
SignNow continues to monitor delivery performance to ensure consistent email delivery to Microsoft-hosted domains.
Resolved: Between February 26 and February 28, Microsoft filtering behavior caused intermittent delivery issues for email invites sent to Microsoft-hosted domains (Outlook, Hotmail, Live, Microsoft 365).
SignNow systems were operating normally, and messages were successfully transmitted and accepted by Microsoft servers. The disruption occurred within Microsoft’s filtering layer due to aggressive spam detection behavior.
Microsoft has identified the issue and is applying backend mitigation (whitelisting) while continuing to tune their detection models.
While awaiting final confirmation from Microsoft, we are proactively re-sending affected unsigned invites to impacted recipients to ensure successful delivery.
We are continuing to monitor delivery behavior closely and will provide updates if needed.
Microsoft confirmed that fix was aplied globally and invites has to be delivered with no further issues. SignNow team will resend all unsgned invites shortly.
SignNow team has resent all affected emails invites.
Monitoring: We are currently awaiting confirmation from Microsoft that the applied fix has been successful.
Monitoring: This incident was caused by aggressive spam filtering behavior within Microsoft-hosted email environments (Outlook, Hotmail, Live, Microsoft 365).
SignNow systems were functioning correctly and emails were successfully accepted by Microsoft servers (SMTP 250 OK). However, Microsoft’s filtering layer intermittently flagged and quarantined certain messages before reaching recipient inboxes.
Microsoft has acknowledged the filtering behavior and applied backend whitelisting for signnow.com as an interim mitigation while tuning their detection models.
The issue is currently mitigated and under monitoring.
Identified: We are still investigating intermittent email delivery issues affecting recipients on Microsoft-hosted domains (including Outlook.com, Hotmail.com, Live.com, and Microsoft 365/Exchange Online environments).
Some emails sent from SignNow to Microsoft-hosted mailboxes are being accepted by Microsoft servers but may not reach the recipient’s inbox. In certain cases, messages may be silently filtered or quarantined.
Identified: The issue has been identified and a fix is being implemented.
Investigating: Issue with sms invites is now being fixed. Email invites still might be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.
Investigating: Some users may experience issues with SMS invite delivery. Additionally, email invites may be routed to spam folders. Our team is actively investigating the issue and will provide updates as they become available.