==== Required information ====
- iRedMail version:
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
- Web server (Apache or Nginx):
- Linux/BSD distribution name and version:
- Related log if you're reporting an issue:
======== Required information ====
- iRedMail version:
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
- Web server (Apache or Nginx):
- Linux/BSD distribution name and version:
- Related log if you're reporting an issue:
======== Required information ====
- iRedMail version: 0.9.0
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Apache
- Linux/BSD distribution name and version: Ubuntu
====

Hi, I'm new user and this is my first post, thanks on big project and I would be very thankfull if you somebody can help me.

I have mail server runing on IRedMail/MySql/Apache/Ubuntu and almost everything is working fine, but i have small problem,
I can't send email form user1@mydomain.com to user2@mydomain.com using external smtp server (my ISP provider smtp server) and mozilla thunderbird email client. I recive delivery status notification email and it is like this:

The following message to <user2@mydomain.com> was undeliverable.
The reason for the problem:
5.1.0 - Unknown address error 553-'5.7.1 <user1@mydomain.com>: Sender address rejected: not logged in'

Reporting-MTA: dns; smtp.myisp.com

Final-Recipient: rfc822;user2@mydomain.com
Action: failed
Status: 5.0.0 (permanent failure)
Remote-MTA: dns; [217.199.131.100]
Diagnostic-Code: smtp; 5.1.0 - Unknown address error 553-'5.7.1 <user1@mydomain.com>: Sender address rejected: not logged in' (delivery attempts: 0)

And if I try to send email from user1@mydomain.com to user@someotherdomain.com or gmail or everywhere using mozilla thunderbird, the same external smtp server and other settings everything working fine.

Can you please help me with this issue?
Best regards