Overview
By default, the Webuzo mail server (Exim) identifies itself during the SMTP handshake using the system's global hostname.
In a multi-tenant environment, this can lead to branding inconsistencies and potential deliverability issues.
This guide explains how an administrator can implement a mapping system to ensure that each domain identifies itself with its own specific mail hostname (e.g., mail.yourdomain.com).
Steps:
The administrator must first create a central mapping file that defines which hostname should be used for each domain hosted on the server.
1. Log in to your server via SSH as the root user.
2. Create or edit the mapping file located at /etc/mailhelo:
nano /etc/mailhelo3. Add the domains and mail HELOs you would like these domains to use with the domain.name: domain.helo format:
example.com: example.com
sub.example.com: example.com
example.net: example.net
addon.example.net: example.net
*: hostname.example.com4. Save and exit the editor (Ctrl+O, Enter, Ctrl+X).
5. Restart Mail Services
systemctl restart exim