Outage in Fastmail
Replies sent using masked email addresses are bouncing
Resolved Minor
September 24, 2026 - Started 7 days ago
- Lasted about 1 hour
Incident Report
Summary AI Generated
Fastmail experienced a 52-minute issue where replies sent from masked email addresses bounced with errors instead of being delivered, affecting mail delivery. Developers identified the root cause and worked toward a fix. A workaround was available by manually adding the sender address under Settings → My email addresses.
We're currently experiencing an issue where replies sent from masked email addresses are bouncing with an error instead of being delivered. Our team is investigating the issue.As a workaround, please add the email address you're looking to send emails from under Settings → My email addresses. You'll then be able to send emails from that address.
Components affected
Fastmail Mail deliveryTrusted by 1,000+ teams
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Latest Updates ( sorted recent to last )
INVESTIGATING
8 days ago - at 09/23/2026 08:00PM
We're currently experiencing an issue where replies sent from masked email addresses are bouncing with an error instead of being delivered. Our team is investigating the issue.As a workaround, please add the email address you're looking to send emails from under Settings → My email addresses. You'll then be able to send emails from that address.
IDENTIFIED
7 days ago - at 09/24/2026 06:48AM
Our developers have identified the issue and are working towards a fix.
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