==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.7 MARIADB edition
- Linux/BSD distribution name and version: Debian GNU/Linux 8
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Apache
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Hello,

Have such situation:
domain1.com on iredmail server
domain2.com on another linux box

When I send email from user1@domain1.com to user2@domain2.com and user2@domain2.com have auto mail forward to user2@domain1.com I have such delivery error:

postfix/postscreen[31022]: WHITELISTED [2.2.2.2]:38945
postfix/smtpd[31023]: connect from mail.domain2.com[2.2.2.2]
postfix/smtpd[31023]: NOQUEUE: reject: RCPT from mail.domain2.com[2.2.2.2]: 554 5.7.1 <user2@domain1.com>: Recipient address rejected: SMTP AUTH is required, or it is a spam with forged sender domain; from=<user1@domain1.com> to=<user2@domain1.com> proto=SMTP helo=<mail.domain2.com>

For example if I send from gmail account to user2@domain2.com mail is forwarded without problems to user2@domain1.com. The problem only exist when I send with iredmail server. Is it possible to fix this?

I've already added mail.domain2.com ip address to postfix mynetworks and to whitelist through wblist_admin.py.

Regards