Outlook 365 Add-in: signatures loading with delays

Update timeline

1. investigating May 07, 2025, 10:00 AM UTC

   We are investigating an issue where the Outlook 365 Add-in is experiencing delays in loading email signatures for some users.

2. resolved May 07, 2025, 10:01 AM UTC

   This incident has been resolved.

3. postmortem May 13, 2025, 12:19 PM UTC

   ## Description The Outlook 365 Add-in encountered an issue where email signatures failed to load promptly for a subset of users. The delay was noticeable when users opened the email composition window, causing a degraded user experience. The issue was reported by multiple users across different regions and was traced back to internal changes in how image URLs are processed within the add-in. ## Root Cause The issue was caused by recent internal changes to the image URL processing logic in the Outlook 365 Add-in. Specifically, a new validation step for image URLs introduced unintended latency when fetching signature images from external servers. ## Impact * **User Experience**: Delays in signature loading when composing emails. * **Business Impact**: No critical data loss or security issues. ## Resolution 1. **Immediate Action**: Deployed a temporary workaround to bypass the new URL validation step, reducing latency for affected users. 2. **Permanent Fix**: Rewrote the image URL processing logic to optimize performance and remove excessive validation checks. 3. **Deployment**: Rolled out the fix to production after thorough testing in a staging environment. 4. **Monitoring**: Post-deployment monitoring confirmed that signature loading times returned to normal.