==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.6.7
- Deployed with iRedMail Easy or the downloadable installer? downloadable
- Linux/BSD distribution name and version: Ubuntu 22.04 LTS
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): NGinx
- Manage mail accounts with iRedAdmin-Pro? no
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Hi,

I have been looking into a locally hosted mail server which is primarily for automated emailing from an app hosted on the same network, Will only be very low amounts of emails.

I have server setup and working, I can login externally via my own sub-domain secured via Lets Encrypt and can send and receive emails.

I already had a Nginx reverse proxy setup for other elements and have routed the mail server through that, meaning the essential route for traffic coming in is:

Router > Nginx Reverse Proxy (192.xx.xx.x1) > iRedMail Server (192.xx.xx.x2)
This works fine to allow access to the web interface for mail, admin etc.  I have also got Nginx setup on the iRedMail server to manage the web interfaces looking at port 443 (routed via the Reverse Proxy).  Port 587 is NAT'd from the router to the iRedMail server and Firewall is setup to allow.

What I am having an issue with, which may be specific to the app (asking for some assistance there aswell), but as I am not sure I am covering the bases.

When I input the server details in the app;
- server name (as per my domain host, MX records are setup etc)
- port 587
- username and password (I know these are correct as I can login fine via the web interface directly).

Any info or pointers would be helpful.  I am no expert, this is the first mail server I have setup and I did try a few options before settling on iRedMail (struggled getting the others to work).

If you want any more info please let me know.

Cheers