How to Configure Email Forwarding Safely in Plesk

Safe Plesk email forwarding

Forward only the addresses you use and reject mail sent to unknown recipients

Create a mailbox or alias for every genuine address, then configure forwarding only on those addresses. In the domain’s Plesk mail settings, set mail for non-existent recipients to Reject. This keeps valid addresses working without creating a domain-wide catch-all for spam sent to random names.

Open the Client Area See the recommended setup
CREATEReal addresses firstMailboxes, aliases and explicit forwarders
FORWARDNamed recipients onlyNo domain-wide catch-all
REJECTUnknown recipientsRefuse random addresses during delivery

Why should you avoid a domain-wide catch-all?

A catch-all accepts messages sent to any name at your domain, even when that address was never created. Spammers commonly send to automatically generated names such as admin123@yourdomain.co.uk or accounts847@yourdomain.co.uk. If Plesk accepts and forwards all of this mail, the destination receives unnecessary spam and the UKC server must process and send it onwards.

External forwarding can pass incoming spam to another provider. Large volumes of unwanted forwarded mail may be treated as suspicious by the destination provider and can affect the forwarding server’s mail reputation. Using only genuine named recipients reduces this risk.

When should you use an email alias?

An alias is an additional address attached to an existing Plesk mail account. Use an alias when the same person or team should receive mail sent to several names.

Use an alias for an alternative name

If your existing mailbox is colin@domain.co.uk, add sales as an alias when messages for sales@domain.co.uk should arrive in Colin’s mailbox.

Use a separate mailbox for a separate inbox

Create a mailbox when the address needs its own password, storage, folders or email-app login.

Use forwarding for a named external destination

Enable forwarding on one real address when its messages genuinely need to be sent to an inbox hosted elsewhere.

Do not use a catch-all to remember old addresses

Create each historic address you still require as an explicit alias or forwarder. Ask UKC before changing the policy if you are unsure which addresses remain in use.

How do you add an alias in Plesk?

  1. 1
    Open Mail

    Sign in to Plesk and open Mail for the correct domain.

  2. 2
    Select the existing address

    Choose the mailbox that should receive messages sent to the alternative address.

  3. 3
    Add the alias

    Open Email Aliases, enter the additional name, save the change and send a test message from an unrelated account.

How do you configure forwarding for one address?

  1. 1
    Create or select the real address

    In Plesk Mail, create the required mail account or select an existing one. Do not configure forwarding for an address nobody genuinely uses.

  2. 2
    Open Forwarding

    Open the address, select the Forwarding tab and switch on mail forwarding.

  3. 3
    Enter the exact destination

    Add the external or internal recipient that should receive this address’s messages. Check the spelling carefully.

  4. 4
    Choose whether Plesk keeps a copy

    By default, Plesk keeps forwarded messages in the local mailbox. Review the available option if you do not want local copies, then save and test.

When several alternative addresses all belong to the same mailbox, create them as aliases of that mailbox. When different addresses need different external destinations, configure each genuine address explicitly.

How do you reject mail for non-existent recipients?

First create every mailbox, alias and explicit forwarding address that the business needs. Then apply the unknown-recipient policy:

  1. 1
    Open the domain’s mail settings

    In Plesk, go to Mail and choose Mail Settings for the correct domain.

  2. 2
    Find mail for non-existent recipients

    This controls messages sent to names that are not configured as a mailbox, alias or other valid mail address.

  3. 3
    Select Reject

    Do not select Forward to address. Save the setting after checking that every required recipient already exists.

What happens when Plesk rejects an unknown address?

Message destinationWhat Plesk doesResult
An existing mailboxAccepts the message for the configured mailboxNormal mailbox delivery continues
An alias of an existing addressRecognises the alias as a valid recipientThe message reaches its associated address
An explicitly configured forwarderAccepts the valid recipient and applies its forwarding ruleThe message is sent to the configured destination
A random or misspelt address that does not existRefuses that recipient during SMTP deliveryThe server does not accept and forward it as catch-all mail

SMTP is the system mail servers use to deliver email. Rejecting the unknown recipient during this conversation means the UKC server does not first accept the message and then try to forward it elsewhere.

Safe forwarding checklist

List the addresses you genuinely use

Include public contact addresses, staff addresses, old addresses still shown on invoices and addresses used by websites or services.

Create each address explicitly

Use a mailbox, an alias of a mailbox or a named forwarder. Do this before changing the unknown-recipient policy.

Set unknown recipients to Reject

In Mail Settings, make sure Forward to address is not selected for non-existent recipients.

Test from outside your domain

Send to every important address from another provider. Confirm the expected local or external inbox receives it.

Plesk forwarding questions

Will Reject stop mail to my real addresses?

No. Mailboxes, aliases and explicitly configured forwarders are valid recipients. Reject applies only when the recipient name does not exist in the domain’s mail configuration.

Is an alias the same as forwarding?

No. An alias is another address for an existing Plesk mail account. Forwarding sends messages received for a valid address to another destination.

Why is Forward to address for non-existent recipients risky?

It creates a catch-all. The server accepts mail sent to every random or mistyped name at the domain and forwards it to one destination, including unwanted mail.

Can external forwarding affect delivery?

Yes. Forwarding can send incoming spam onwards and can interact with SPF, DKIM and DMARC checks. Destination providers may reject or filter some forwarded messages. Use forwarding only for genuine recipients and test important routes.

Should I delete an old address before setting Reject?

Only if you are sure it is no longer used. If an old address may still receive customer, supplier or account messages, preserve it as an explicit mailbox, alias or forwarder, or ask UKC to help you review the setup.

Where are these controls in Plesk?

Aliases and forwarding are configured by opening an address under Mail. The policy for non-existent recipients is under Mail, then Mail Settings for the domain. The wording can vary slightly with the Plesk view and permissions available to the account.

Check the addresses before changing the policy

Create genuine recipients, reject everything else

Use explicit mailboxes, aliases and forwarders so wanted mail has a clear destination without turning the whole domain into a catch-all.

Ask UKC Support Open the Client Area
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