Setting up aliases and a catchall

Aliases are forwarding rules. A mail to info@yourdomain.de lands in the mailbox firstname@yourdomain.de without info@ needing its own mailbox with its own storage. Useful for role addresses, old mail addresses that should still be passed through, and typo protection via a catchall.

Creating a simple alias

In the Mailcow GUI:

1. Configuration → Aliases.
2. Click Add.

In the dialog:

Field	Value
Alias address	info@yourdomain.de (the address that should receive mail)
Target mailbox	full mail address of the mailbox the mails should land in
Active	enabled
Public distribution list	only enable if you want a mailing list (multiple recipients)

Save. Active immediately — mail to info@yourdomain.de now lands in the target mailbox.

Multiple targets for one alias

You can set several recipients per alias — info@ then goes to Firstname1, Firstname2 and Firstname3. In the target mailbox field, separate the addresses with commas or enter each mail individually.

That effectively turns the alias into a small mailing list. Careful: when a recipient replies, the reply goes to the original sender, not back through the alias. That’s normal mailing-list behavior.

Aliases with wildcards / patterns

Mailcow supports simple patterns:

• Suffix: support+alpha@yourdomain.de and support+beta@yourdomain.de both land in the same mailbox if you enable it (plus addressing).

You enable plus addressing in the mailbox edit under TLS options → Enable plus addressing. Useful for finding out where spam comes from — when you sign up on a website, you give firstname+website@yourdomain.de, and later you’ll see when spam arrives with that suffix.

Setting up a catchall

A catchall is a “catch everything” alias: every mail to your domain whose recipient address has neither a mailbox nor another alias lands in the catchall mailbox.

Setup:

1. Configuration → Aliases → Add.
2. Alias address: @yourdomain.de (just the @ plus domain, no local part).
3. Target mailbox: your collection mailbox.

Save.

From now on, mail to typo@yourdomain.de, unknown@yourdomain.de or anything else lands in the target mailbox.

Careful — a catchall attracts spam: spam senders guess addresses in bulk — info@, kontakt@, firstname@, 123@, sales@. With a catchall you catch all of it. From our experience: in the first 4 weeks after enabling a catchall, incoming spam volume often doubles.

If that gets annoying: disable the catchall and create targeted aliases for the important role addresses instead (info@, kontakt@, support@).

Aliases across domains

If you have several domains in your Mailcow plan, you can create aliases across domains. info@yourclub.de can point to firstname@yourotherclub.de.

Requirement: both domains are set up in your Mailcow plan.

Domain aliases

Special case: you have a main domain and an alias domain — say myclub.de as the main domain and myclub.com as the alias domain. All mail to *@myclub.com should go to the matching local address on myclub.de.

Configuration → Domain aliases → Add:

• Alias domain: myclub.com
• Target domain: myclub.de

From now on, info@myclub.com automatically lands in info@myclub.de. Works for all local parts without you creating each one individually.

Domain aliases are more efficient than individual aliases per local part — especially when both domains should have exactly the same mailbox structure.

Best practices

Role addresses as aliases, not as mailboxes. info@, support@, vertrieb@ should be aliases pointing to personal mailboxes. Advantage: no extra storage, easy to reroute when the responsible person changes.

Rewire the aliases when someone leaves. When Firstname Miller leaves and Firstname Smith takes over, change the alias targets — no mail to info@ has to get lost.

Use the catchall with care. We only recommend a catchall if you really want to see every typo mail and accept the extra spam. For most people, a list of targeted aliases is enough.

Clean up aliases regularly. Over the years, aliases nobody uses anymore tend to pile up. Go through them once a year and remove the old ones.

Frequently asked questions

Do aliases count against the plan limit? Aliases don’t count against the mailbox limit. You can create practically unlimited aliases as long as the target mailbox exists.

Can aliases send, or only receive? By default, receive only. If you want to reply as info@yourclub.de, there are two ways:

1. In SOGo webmail: set up multiple “identities” per mailbox (Settings → Identities). When composing, you can then pick from several addresses.
2. In Outlook/Apple Mail/Thunderbird: similar — add an additional sender address per account.

For the mail server to allow sending as info@, the alias has to be added as a permitted sender in the mailbox configuration under sender restrictions.

What happens when an alias points to a non-existent address? Mailcow rejects the incoming mail. Bounce to the sender. Practical tip: after deleting a mailbox, delete or rewire its aliases.

Can aliases point to external mail addresses? Yes. You can also forward info@yourclub.de to partner@externaldomain.de. That’s a regular forward — but not all spam filters play along. Receiving mail servers sometimes bounce forwarded spam back to you because you appear as the sender. From our experience: fine with 1–2 forwards; with many, better to use a dedicated collection mailbox.

Can I combine aliases with Sieve filters? In the target mailbox you can sort via Sieve filters — for example “put mails that were addressed to info@ into the ‘info’ folder”. More in Personal Sieve filters in webmail.

What does “public distribution list” mean? If enabled, anyone on the internet (even without auth) can write to the alias address — which is usually what you want. If disabled, Mailcow rejects external mail to this alias — only authenticated internal senders get through. Useful for internal-only distribution lists.

What’s next

• Creating and editing mailboxes, setting quotas
• Personal Sieve filters in webmail
• SOGo webmail — first login and overview