Allow plain authentication for IMAP

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1

Your question

How do I allow for a listener with IMAP protocol AND without TLS plain authentication?

I know the security implications and it’s NOT over a public network.

I’m using Stalwart v0.16.

I understand that topics in this category are triaged by a bot first but a human reply will follow up. If I’d prefer a human-only reply, I’ll add the no-ai tag to my topic.

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2

I have the answer now.

To allow IMAP clients to authenticate with plain credentials over an unencrypted connection, enable the allowPlainTextAuth field on the Imap settings object (Settings › Network › IMAP in the WebUI). It defaults to false.

Via the WebUI, go to Settings → Network → IMAP and toggle “Allow plain text authentication” on.

Via stalwart-cli:

stalwart-cli update Imap --field allowPlainTextAuth=true

Or via the JMAP API with an x:Imap/set call updating the singleton record’s allowPlainTextAuth field to true.

This setting is separate from TLS configuration on the network listener itself: it only controls whether the IMAP protocol layer accepts cleartext credentials, not whether the listener has TLS enabled at all. Since you’ve noted this is on a trusted network, enabling it is sufficient without any listener-level TLS changes.

Reference: Imap | Stalwart

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