==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release):
- Deployed with iRedMail Easy or the downloadable installer?
- Linux/BSD distribution name and version:
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
- Web server (Apache or Nginx):
- Manage mail accounts with iRedAdmin-Pro?
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====
- 1.6.0 MARIADB edition
- Deployed with downloadable installer
- Debian 11 (bullseye)
- Backend: MySQL
- NginX
- not using iRedAdmin-Pro
====

Symptom: I'm unable to send/receive email from my external domain, ericmintz.com. My SMTP server is mx.emsquared-inc.com

Thanks in advance!

~~~
From /var/log/iredapd/iredapt.log:
... using the ping tool from mxtoolbox
~~~

Jun 27 12:00:12 mx iredapd [18.205.72.90] RCPT, supertool@mxtoolboxsmtpdiag.com -> test@mxtoolboxsmtpdiag.com, DUNNO [sasl_username=, sender=supertool@mxtoolboxsmtpdiag.com, client_name=keeper-us-east-1c.mxtoolbox.com, reverse_client_name=keeper-us-east-1c.mxtoolbox.com, helo=keeper-us-east-1c.mxtoolbox.com, encryption_protocol=, encryption_cipher=, server_port=25, process_time=0.3592s]
Jun 27 12:01:39 mx iredapd [127.0.0.1] RCPT, emintz@ericmintz.com => ping@tools.mxtoolbox.com, DUNNO [sasl_username=emintz@ericmintz.com, sender=emintz@ericmintz.com, client_name=mx.emsquared-inc.com, reverse_client_name=mx.emsquared-inc.com, helo=localhost, encryption_protocol=TLSv1.3, encryption_cipher=TLS_AES_256_GCM_SHA384, server_port=587, process_time=0.0045s]
Jun 27 12:01:39 mx iredapd [127.0.0.1] END-OF-MESSAGE, emintz@ericmintz.com => ping@tools.mxtoolbox.com, DUNNO [recipient_count=1, size=358, process_time=0.0012s]

Jun 27 12:28:20 mx iredapd [127.0.0.1] RCPT, emintz@ericmintz.com => ping@tools.mxtoolbox.com, DUNNO [sasl_username=emintz@ericmintz.com, sender=emintz@ericmintz.com, client_name=mx.emsquared-inc.com, reverse_client_name=mx.emsquared-inc.com, helo=localhost, encryption_protocol=TLSv1.3, encryption_cipher=TLS_AES_256_GCM_SHA384, server_port=587, process_time=0.0043s]
Jun 27 12:28:20 mx iredapd [127.0.0.1] END-OF-MESSAGE, emintz@ericmintz.com => ping@tools.mxtoolbox.com, DUNNO [recipient_count=1, size=358, process_time=0.0010s]