I'm afraid that we need a new smtp port for SOGo in this case, but with default iRedMail settings, it works fine.
*) Add new lines in /etc/postfix/master.cf:
127.0.0.1:2525 inet n - n - - smtpd -o syslog_name=postfix/plain-smtp-2525 -o smtpd_sasl_auth_enable=yes -o smtpd_tls_security_level=may -o smtpd_client_restrictions=permit_sasl_authenticated,reject -o content_filter=smtp-amavis:[127.0.0.1]:10026*) In /etc/sogo/sogo.conf, update "SOGoSMTPServer" setting:
SOGoSMTPServer = 127.0.0.1:2525;*) Restart both postfix and sogo services.
I was able to resolve the issue - It was discovered that someone had followed this doc:
https://docs.iredmail.org/allow.insecur … tions.html
Section: Allow insecure SMTP connection on port 25
Once I undid these changes I was able to send mail from iOS again. I believe that your solution above would have also resolved the issue. The changes to port 25 were done while testing a multifunction device, but it was ultimately not used. The changes were never backed out.
Thank you for all the help on this!