Postal
ERROR: An error occurred while attempting to establish an SSL or TLS connection in Postal smtp #1458
Replies: 15 comments 6 replies
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If you have recently changed the config file, you will need to restart Postal to apply the changes. Have you changed the ciphers or anything under those lines of config? Can the postal user definitely access those certificate files you have mentioned? |
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tls working fine but when i test smtp then show me this error Error: OpenSSL::SSL::SSLError (hostname "myhost.com" does not match the server certificate) |
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run the command openssl s_client -connect myhost.com:25 -starttls smtp and paste the output |
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CONNECTED(00000005)
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try to send on 587 for tls |
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140663099892160:error:0200206F:system library:connect:Connection refused:../crypto/bio/b_sock2.c:110: i get this. |
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try this smtp_server: |
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postal not working if i put port 587 |
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check the logs and paste screenshot here of error |
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please do send the screenshot of postal.yml Note: Please do hide private information in Screenshot or code |
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I'm also facing the same issue. this is my yml file smtp_server: |
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Hello i am writing this answer because i also struggled to establish a working TLS setup for SMTP. These are the steps i took to make it work. i copied the the certificates from caddy to the correct folder in postal and changed permissions accordingly: after that i altered my postal.yaml to this: please note: the path starts with Stop and restarted postal. first i encountered some error messages when running this command this is what i found in the logs (docker logs postal-smtp-1) so far: but after i corrected the the pathes in the |
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hi, what paths did you enter in postal.yaml? I'm trying: or But it does not work: |
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Hey plancked, i did as i wrote in my little tutorial (with a beginning "/". |
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so certificate files are in /opt/postal/config ? |
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@rakurtz Do you have any idea how much time I spent trying to solve this problem? And to make matters worse, I still don’t understand exactly what went wrong. I followed your exact steps, but the only difference was that I didn’t include these two lines: And it didn’t work! I spent the whole day trying various configurations, but I kept getting this error message: I tried both a Certbot-generated SSL certificate and a self-signed one, but still no luck. Then, I found your solution, added the two lines you mentioned, and granted read permission for others on both files — and suddenly it works! What a relief! Postal really needs to fix this and automate this configuration for end users. It was a total nightmare. I did just like you did and now it suddenly works! Also, just an extra note: if you’re setting up SSL for mail servers, you should generate a certificate not only for the main domain but also for the MX records. A common cause of the "hostname mismatch" error is when the certificate issued (by Caddy, in my case) for mail.example.com doesn’t include the mail servers (mx1.mail.example.com and mx2.mail.example.com) as Subject Alternative Names (SANs). To fix this, you should issue a certificate that includes all the necessary subdomains. For example, the certificate should include:
You can issue this certificate using Certbot with the following command: I haven’t tested it fully yet, but I’m testing it now. |
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Hey mate, i remember: This was a total nightmare to solve. It seems very unclear and different sources in the internet say different things. I am glad i took the time to write my comment above and was able to help you. Best of luck for you |
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I've written a comprehensive guide about setting up Postal. It covers setting up SMTP TLS in detail. |
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@ivansalloum thank you so much for your lovely guide. I also spend quite some time since Sunday because of lack of documentation. Hopefully maintainer will find some time to implement your steps. May I asked how you connect your mail client? When using Thunderbird it gives me after enable tls: smtp-1 | 2025-11-05 10:25:30 +0000 DEBUG Connection opened from IP trace_id=YJNVQ2KA component=smtp-server |
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can't connect postal SMTP via tls Its shows an error.
Connected to smtp://mydomain:25/?starttls=always
<< 220 mydomain ESMTP Postal/SVYGBU
It is also possible that the set of SSL/TLS protocols supported by the client and server do not match.
See https://github.com/jstedfast/MailKit/blob/master/FAQ.md#SslHandshakeException for possible solutions.
See SMTP server configuration in postal.yml
smtp_server:
tls_enabled: true
tls_certificate_path: /etc/letsencrypt/live/domain/fullchain.pem
tls_private_key_path: /etc/letsencrypt/live/domain/privkey.pem
@willpower232
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