We use Mailgun SMTP to send emails. In the main.cf of postfix we added the usual relay / sasl settings:
# Amavisd + SpamAssassin + ClamAV # content_filter = smtp-amavis:[127.0.0.1]:10024 # Concurrency per recipient limit. smtp-amavis_destination_recipient_limit = 1 relayhost = [smtp.mailgun.org]:587 smtp_tls_security_level = encrypt smtp_sasl_auth_enable = yes smtp_sasl_password_maps = static:firstname.lastname@example.org:password smtp_sasl_security_options = noanonymous
Works fine and email deliveries are properly logged under Mailgun.
If we send an email within our domain, Mailgun will not be triggered. Medium: if JohnDoe @abcDomain.com sends an email to JaneDoe @abcDomainwill be delivered via Postfix. If JohnDoe @abcDomain.com sends an email to JohnDoe @xyzDomain.com, which is part of another domain, is delivered and logged via Mailgun smtp.
We have no explanation for this behavior. Maybe we missed something?
Thank you for every hint