Thursday August 7, 2025

Between 12:20 PM PDT on August 6, 2025, and 8:50 AM PDT on August 8, 2025, some users may have experienced delays in receiving Slack-related emails, including those for logging in.

An automated alerting system flagged potential latency issues with our email delivery. We promptly investigated the issues and collaborated with our upstream provider to identify the root cause. Our investigation revealed an unexpected restriction on the backend service responsible for email routing, which led to the delays. After our provider addressed this restriction, emails began delivering as expected, resolving the issue for all affected users.

11:40 AM PST

The issue is now resolved, and users should no longer be experiencing any trouble with emails. Apologies for the trouble, and thank you for your patience.

11:15 AM PST

We’ve begun partnering with an upstream provider to help with our investigation and are waiting on additional details from their analysis. Emails are still reaching end users, but some may still be delayed. We’ll be back with another update as soon as we receive more information from our partners.

5:47 PM PST

Our investigation into the email delivery delays is still ongoing. However, we've determined that this is primarily affecting users with @outlook.com, @hotmail.com, or similar email addresses. We'll  keep you posted as soon we have an update.

3:11 PM PST

We're investigating an issue where some users are experiencing delays in receiving emails, including those related to logging in. These emails are reportedly taking up to several hours to arrive. We'll provide another update as soon as we have more news to share. We apologize for the trouble in the meantime.

2:38 PM PST

We've identified a new incident that is now resolved for all users. Below is a summary:

Between 7:09 AM and 7:28 AM PDT on August 7, 2025, some users may have experienced intermittent errors or latency with several Slack features. This brief issue could have caused delays when performing actions such as searching, messaging, and using administrative tools.

An internal health dashboard alerted us to an unusual spike in traffic to one of our backend caching systems, which caused timeout issues. This primarily impacted users on Enterprise Grid, though a number of non-enterprise users may also have been affected.

To quickly mitigate the impact, we temporarily redirected traffic away from the problematic caching service to allow it to stabilize. We also implemented additional measures to help reduce the impact of future traffic spikes. Once our internal metrics returned to normal, we reverted traffic back to its standard routes. All features are working as expected.

4:36 PM PST