Hey guys, I have a problem with Mailcow. When I try to send an email to an internal email address it works fine, but as soon as I want to send an email via SMTP (e.g. Moodle) to an external address e.g. gmail it doesn't work anymore and I get the following in the Postfix log. Strangely enough, I can send an e-mail to any e-mail address manually via SoGo. ```log 06.05.2024, 18:51:18 info disconnect from mail..net[] ehlo=2 starttls=1 mail=1 rcpt=0/1 quit=1 commands=5/6 06.05.2024, 18:51:18 info NOQUEUE: reject: RCPT from mail..net[]: 554 5.7.1 : Relay access denied; from= to= proto=ESMTP helo= 06.05.2024, 18:51:13 info discarding EHLO keywords: CHUNKING 06.05.2024, 18:51:13 info Anonymous TLS connection established from mail..net[] to mail..net: TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 06.05.2024, 18:51:13 info discarding EHLO keywords: CHUNKING 06.05.2024, 18:51:13 info connect from mail..net[] 06.05.2024, 18:51:13 info WHITELISTED []:36732 06.05.2024, 18:51:13 info CONNECT from []:36732 to []:25 ``` It would be very helpful if anyone could help me!

@"esackbauer"#p15556 thank you for your answer, that suprises me because my reverse DNS is set to mail..net, I don't know why is could be moodle..net if I send for example a test mail from a other software the helo is serverpanel..net - is is possible that this is a problem with my mailcow/postfix config? [upl-image-preview url=https://community.mailcow.email/assets/files/2024-05-06/1715018421-326487-image.png]

@"esackbauer"#p15580 I am not sure, but I guess everything should be correct with the PTR-record: [upl-image-preview url=https://community.mailcow.email/assets/files/2024-05-07/1715103223-680770-image.png] (mailcow ui)

Can't send mails to external addresses

lion_king287

Hey guys, I have a problem with Mailcow. When I try to send an email to an internal email address it works fine, but as soon as I want to send an email via SMTP (e.g. Moodle) to an external address e.g. gmail it doesn’t work anymore and I get the following in the Postfix log. Strangely enough, I can send an e-mail to any e-mail address manually via SoGo.

06.05.2024, 18:51:18	info	disconnect from mail.<DOMAIN>.net[<IP>] ehlo=2 starttls=1 mail=1 rcpt=0/1 quit=1 commands=5/6
06.05.2024, 18:51:18	info	NOQUEUE: reject: RCPT from mail.<DOMAIN>.net[<IP>]: 554 5.7.1 <<MAIL>@gmail.com>: Relay access denied; from=<noreply@<DOMAIN>.net> to=<<MAIL>@gmail.com> proto=ESMTP helo=<moodle.<DOMAIN>.net>
06.05.2024, 18:51:13	info	discarding EHLO keywords: CHUNKING
06.05.2024, 18:51:13	info	Anonymous TLS connection established from mail.<DOMAIN>.net[<IP>] to mail.<DOMAIN>.net: TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256
06.05.2024, 18:51:13	info	discarding EHLO keywords: CHUNKING
06.05.2024, 18:51:13	info	connect from mail.<DOMAIN>.net[<IP>]
06.05.2024, 18:51:13	info	WHITELISTED [<IP>]:36732
06.05.2024, 18:51:13	info	CONNECT from [<IP>]:36732 to [<IP>]:25

It would be very helpful if anyone could help me!

esackbauer

Get your reverse DNS to point properly at mail.domain.net. Yours is pointing to "moodle.dmain.net:

helo=<moodle.<DOMAIN>.net>

lion_king287

esackbauer thank you for your answer, that suprises me because my reverse DNS is set to mail.<domain>.net, I don’t know why is could be moodle.<domain>.net if I send for example a test mail from a other software the helo is serverpanel.<domain>.net - is is possible that this is a problem with my mailcow/postfix config?

esackbauer

No, reverse DNS config is done only with your hosting provider.

Please check again if you really follow the DNS Setup:
https://docs.mailcow.email/getstarted/prerequisite-dns/

lion_king287

esackbauer I am not sure, but I guess everything should be correct with the PTR-record:

(mailcow ui)

esackbauer

why does googles smtp server then thinks your server is named moodle.domain.net? Have you set this somewhere as hostname? Do you use a different MTA/Relay?