Activate and Test Mail for an Additional Domain on a DirectAdmin VPS

This checklist activates mail services and performs live send/receive testing for an additional domain on an existing DirectAdmin VPS. Server-level mail infrastructure was already established earlier. This post applies only the per-domain steps required to validate real-world mail delivery before DMARC authentication.

Prerequisites and strict sequencing

• The additional domain has been added to the DirectAdmin VPS.
• Authoritative DNS is live.
• SSL is active and verified for the domain.
• Supporting services (Redis and DirectAdmin Extra Features) are confirmed operational.

If any prerequisite is incomplete, stop and return to the appropriate earlier step.

Create the domain mail identity

A mailbox identity must exist before DKIM can be enabled.

• Create Domain Admin Mailbox Identity in DirectAdmin using Roundcube

Enable DKIM for the additional domain

DKIM is required before live testing and must be enabled per domain.

• Enable DKIM for the domain in DirectAdmin.
• Confirm DKIM status shows as active.

Configure rDNS (server-level, verify only)

Reverse DNS applies to the server IP and is performed only once. At this stage, it’s only an option to confirm it is already configured.

• Optionally, verify rDNS matches the server hostname.

If rDNS was not previously completed, stop and follow:

• Add rDNS, if not done previously on the Account Domain checklist.

Run live mail tests using Gmail

Live testing must be performed using Gmail to validate real-world deliverability.

1. Send a test email from the domain mailbox to a Gmail address.
2. Reply from Gmail back to the domain mailbox.
3. Confirm:
   • Messages are delivered successfully
   • No warning indicators appear

Handle mail port failures

Mail ports are not assumed to be open. However, this was intentionally an entire section (to ensure they’re open) on the Account Domain creations checklist.

• If sending or receiving fails, do not proceed further.
• Revisit the post on how to Activate and Test Mail for the Account Domain.

Use this procedure if escalation is required:

• Mail Open Ports Request

Stop point before DMARC

• Do not configure DMARC yet.
• Do not add SPF or additional mail routing changes.

DMARC authentication depends on confirmed DKIM and successful live mail testing.

Next step:
Proceed to the next post to Authenticate Domain Mail with DMARC.