Team Server 10.1.*: Fail to connect to SMTP using TLS

Troubleshooting
1

Summary
Team Edition 10.0.1 server works well with this configuration

    "EmailSettings": {
        "EnableSMTPAuth": true,
        "SMTPUsername": "mattermost",
        "SMTPPassword": "***",
        "SMTPServer": "mail.***.ru",
        "SMTPPort": "465",
        "SMTPServerTimeout": 10,
        "ConnectionSecurity": "TLS",
        "SkipServerCertificateVerification": true
    }

After installing version 10.1.* got this error:
{"timestamp":"2024-10-25 13:21:53.750 Z","level":"error","msg":"Connection unsuccessful: unable to connect to the SMTP server through TLS: remote error: tls: handshake failure","caller":"web/context.go:124","path":"/api/v4/email/test","request_id":"b67i1rhhfpyspfnziux1nhd5fw","ip_addr":"127.0.0.1","user_id":"qjyjbf5o7ifp8pf9pr1kanhp9r","method":"POST","err_where":"testEmail","http_code":500,"error":"testEmail: Connection unsuccessful: unable to connect to the SMTP server through TLS: remote error: tls: handshake failure"}

Reverting to 10.0.1 fixed issue.

Steps to reproduce
Install MM 10.1.2 self-hosted team edition. Setup SMTP with TLS as shown above and click Test Connection in client system console.

2

Hi Iluha! Thank you for providing those details. The update to 10.1 might have introduced new TLS requirements, so I’d recommend double-checking your SMTP settings and certificate compatibility. You might also find helpful troubleshooting tips in our Troubleshooting Mattermost issues documentation. Please let us know if this resolves it or if we can help further!

3

Hi John!

What about parameter SkipServerCertificateVerification - is it still working in 10.1 ?

4

@john.combs

The update to 10.1 might have introduced new TLS requirements

I didn’t find any info about this in
https://docs.mattermost.com/about/mattermost-v10-changelog.html#release-v10-1-feature-release

5

Mattermost might be a good place to ask.

6

You can also open an issue at Issues · mattermost/mattermost · GitHub