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Plesk: Inbound gateway setup with local mailboxes

Keep Plesk mailboxes enabled on the receiving server while routing inbound mail through Spamless. Check the mail service, MX and ownership TXT, and save the settings needed for rollback.

Support status: recipe_available · Documentation checked: 2026-10-16 · Recipe version: 2026-10-16.1

Manual setup recipe reviewed against official documentation. Live provider delivery has not been verified; there is no automatic provider connector.

Setup steps

1. Save the current settings

Before changing anything, save the authoritative MX, TXT, A/AAAA records, priorities and TTLs, the current mail-routing settings, and the actual mailbox server's hostname and SMTP port. Keep this baseline for rollback.

2. Set the existing mailbox server as the origin

Ask the hosting provider for the direct SMTP hostname of the server that stores your mailboxes, and enter that hostname and port in Spamless. The origin must not resolve to Spamless or route back to this domain's public MX. Do not infer it from MX after the change.

3. Keep local mailbox delivery enabled

In Plesk > Websites & Domains > your domain > Mail Settings, keep Mail service on this domain set to Enabled. Spamless is an inbound gateway, not the mailbox host. Do not select Disabled for incoming mail or Not configured; Not configured removes the domain's existing mailboxes and messages.

Source: Plesk Obsidian: Mail Settings of Domains.

4. Review recipients and unknown addresses

Confirm that a real mailbox and its aliases exist. Review catch-all behavior with your hosting provider; an unknown recipient should be rejected during SMTP where supported, rather than accepted and later bounced. Do not remove intentional aliases or existing catch-all service without agreement.

Source: Plesk Obsidian: Mail Settings of Domains.

5. Check SMTP reachability and TLS

Ask your host to permit SMTP from Spamless's current, support-confirmed relay addresses on the configured origin port. Check STARTTLS and a valid certificate for the origin hostname. Keep relay restrictions; do not enable an open relay or disable certificate checks. Resolve any failed check before moving MX.

6. Publish the domain-specific DNS instructions

Use the exact ownership TXT and MX values shown for this domain in Spamless at the authoritative DNS provider. Preserve existing outbound SPF, DKIM and DMARC settings; merge requested SPF changes into one record. A direct-to-origin backup MX bypasses filtering. Change MX only after saving the baseline and checking the origin.

7. Verify DNS and a complete delivery

Run Spamless's ownership/MX and origin checks. Then start a non-confidential test from an external mailbox you control and confirm its arrival in the destination mailbox, including aliases you use. A green DNS or TLS check alone does not prove end-to-end delivery. Keep the origin and rollback baseline available.

Before switching MX

  • I saved the original DNS records, TTLs and provider routing settings.
  • My host confirmed the direct origin hostname and port; it does not route back to Spamless.
  • The provider still delivers this domain to its local mailboxes.
  • I reviewed real recipients, aliases and catch-all handling.
  • The relay's SMTP access and the origin's TLS configuration are ready.

Routing cautions

  • These instructions apply only when the mailboxes remain on this hosting server; an external mailbox service needs a different routing plan.
  • The origin hostname must remain independent of the public MX. A gateway-to-gateway or MX-to-origin loop prevents delivery.
  • Do not delete mailboxes or change mail-client passwords to install an inbound gateway. Public MX changes do not move stored messages.

Restore your previous setup

  1. Restore the saved DNS baseline — At the authoritative DNS provider, restore the exact saved MX records, priorities and any TXT or address records changed during setup. Use the saved values, never a guessed hostname or a generic example.
  2. Review provider routing and queued mail — Keep mailbox service enabled. Restore only provider settings you actually changed, using the saved baseline and your host's advice. Keep the origin available while cached DNS and previously queued gateway deliveries are reconciled; ask support before removing the Spamless domain.
  3. Confirm direct delivery again — Allow the relevant DNS TTLs to expire and send a new non-confidential external test to your real mailbox. Check both the mailbox and delivery logs; a saved-record restore is not itself proof of delivery.

Official sources

Can’t find what you need? Email us at hello@spamless.dev