Issue Description I created a simple alias for my admin user admin@test.com with the following settings: Local part: postmaster Domain: test.com Enabled: true Sending an e-mail to postmaster@test.com results in an error e-mail Mail Delivery System - Undelivered Mail Rturned to Sender. Within the…

v0.16.10 will automatically invalidate the negative email cache when an account is created.

There isn’t a dedicated docs page for alias configuration that I can ground a detailed answer in, so I’ll note what’s observable from your description and flag it for a human follow-up. A few things worth double-checking in the meantime: postmaster is a reserved address. RFC 5321 requires every …

Also ran the test with another alias john.doe@test.com and it did not work either. Just to make sure, sending and receiving from an to admin@test.com works without any issues.

Please try setting the log level to trace, send a test email and check what the logs report.

It’s not working on my end either. Here is my reproduction path: Environment: Fresh installation of the latest Stalwart mail server (all default settings - RocksDB for all). Setup: Completed initial setup and authentication. Primary Email: Created a primary email account: admin@[example].co…

Just an update on my end: after I went to Actions and cleared both caches (Invalidate all caches and Invalidate negative caches), the email alias started working immediately and could receive emails perfectly. Is this manual cache invalidation always required when creating a new alias? Coming from…

If anything has attempted to interact with that specific address, by default it will be negatively cached for 1 hour unless manually cleared. If you have a script that checks if the mailbox exists before creating it, that would result in a negative cache, that can be cleared via CLI.

E-Mail alias not working

Issues

barthel-eu June 26, 2026, 10:45pm 9

@stalwart This may be related and is not related to negative caching (problem persisting for days): Delivery Failure on specific account

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E-Mail alias not working

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