Disabling chroot doesn't fix the issue, it just worked around it.
Aparently your chroot is not configured correctly, likely using debian
based system, and your resolv.conf in the chroot is not updated
correctly.
Quoting Dan Langille <d...@langille.org>:
I wanted to mention I updated the Postfix and Dovecot SASL wiki
entry yesterday.
http://wiki2.dovecot.org/HowTo/PostfixAndDovecotSASL
The entry:
submission inet n - - - - smtpd
was incorrect. It should be:
submission inet n - n - - smtpd
By specifying n for chroot, it ensures that DNS lookups can occur.
Otherwise, if you are using reject_unknown_recipient_domain
the following error will occur: Recipient address rejected: Domain not found
Hope that helps.
—
Dan Langille
http://langille.org/
