Client mail ne trouve pas le serveur postfix avec le port 587

hi i'm using postfix mail , it work and listen on 25 and 587 port ! but when the email client accept the mail server on port 25 but not when i put le port 587


Hi @bensaidRayen,

I don't think this is a problem related to a Let's Encrypt certificate, so this forum isn't the best place to get help with this issue. Could you try a different forum related to Postfix or Thunderbird instead?

Good luck!

do you think that to use port 587 i don't have to get a certificat ??

You need a certificate to use STARTTLS. However, your post doesn't reflect any certificate issue. Also, the error is in French, which isn't a language spoken by many users here on this Community. So I'm not able to understand what Thunderbird is complaining about.

Also, you're connecting to As answered in your other recent thread, Let's Encrypt can't issue certificates for non-public hostnames or IP addresses.

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