I have an issue I can’t figure out, and that is why postfix is constantly emailing itself, like it is stuck in an unstoppable mail loop?
I can see from the email log that the email is bouncing, because of an unknown user:
Jan 27 02:35:17 mydomain postfix/local.... to=<firstname.lastname@example.org>, relay=local, delay=0.01, delays=0/0/0/0, dsn=5.1.1, status=bounced (unknown user: "inquiry")
But the email exist and the email is used for sending out emails via a contact form on the website, and the email is hosted at Office 365.
I’ve figured out that there might be an issue with the website domain name and the email domain name being the same (externally set up at Office 365), so is there anyone who has experienced the same issue and how to correct it?
Is there anything in my /etc/postfix/main.cf file that should be different to prevent this?
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination relayhost = [smtp.office365.com]:587 myhostname = mydomain.com alias_maps = hash:/etc/aliases alias_database = hash:/etc/aliases mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 mailbox_size_limit = 0 recipient_delimiter = + inet_interfaces = all inet_protocols = ipv4
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I’m not sure if others have experienced this issue, but if your email server is hosted on another domain and you use postfix and SMTP to send local emails from a web form, then you need to setup the following in your postfix configuration.
This forces postfix to always use the external email server, even in a case the email recipient is under your local domain name, like
Please also male sure that
$mydomainis equal to
localdomainand it can be checked with
postconf -d | grep mydomain, otherwise you can set the variable with
mydomain = localdomain.
I figured out that if the recipient is an email with the same domain name
email@example.com the website itself
www.mydomain.com, postfix starts to constantly emailing itself and it get stuck in an unstoppable email loop.
So to prevent this, how can I set up postfix to always use
"postfix/local", which clearly is causing the email bounce loop??
When it comes to e-mail, there’s two files
When an e-mail is sent out, these two files are checked. If the domain is in
localdomains, the mail gets routed locally – if the domain is in
remotedomains, the mail is routed off the server.
Since you’re using an external mail server, I would remove your domain from the local to the remote file. You shouldn’t need to restart any services as these files are checked each time and e-mail is sent.