==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.6.1
- Deployed with iRedMail Easy or the downloadable installer? installer
- Linux/BSD distribution name and version:  Ubuntu 20.04
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  MySql
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? yes
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Hello,
I use google workspace for mydomain.com so MX is set to ASPMX.L.GOOGLE.COM

I configured google workspace to forward email for specific non existing users to iredmail server mail001 .
This is the so called split delivery (support.google.com /a/answer/12971016?hl=en).

I also enabled smtp relay inside google workspace, so the non existing address are allowed to send email by using google smtp.

So an email sent to info@mydomain.com is handled from google servers because info@ is a paid google workspace account.

An email sent to abc@mydomain.com is routed to mail001 because abc@mydomain.com is not a paid google workspace account.

mail001 accept the email because I created abc@mydomain.com.
I can also login into roundcube with abc@mydomain.com. This is expected.

I have issues when I try to send email from abc@mydomain.com from roundcube to info@mydomain.com

I receive error 550 : user doesn't exists.

I suppose this is because roundcube uses 127.0.0.1 as smtp, and the user info@mydomain.com doesn't exists on the local system.

What I want to achieve is the following:

- I want to be able to read emails to abc@mydomain.com on mail001's Roundcube.
- All email sent from any domain hosted on mail001 to mydomain.com should use google smtp instead of local smtp.

It's unclear to me if I have to act on postfix config or roundcube config or both.

I saw the relay options available in the iredadmin pro panel but I haven't figured out how to set it correctly.

Can you help me?

Thanks