Setting Up a Catch-All Inbox

A catch-all inbox captures every email sent to your domain that doesn't match a specific mailbox or alias. Instead of bouncing back to the sender as "550 User not found", we deliver it to a mailbox of your choice. This guide covers when to use it, how to set it up, the spam tradeoffs that catch people out, and how it interacts with aliases.

Why a catch-all

Common reasons to enable one:

• Catch sales leads with typos. Someone trying to email sales@yourcompany.com but typing sles@yourcompany.com — without catch-all, that email bounces and the lead is lost. With catch-all, it lands in your sales inbox with the wrong address visible in the To header, so you still see what the sender thought they were sending to.
• Use dynamic aliases without creating them first. Sign up to a new service as service-name@yourcompany.com. Receive verification emails to that address. Move on. Useful for solo founders who want per-service tracking without managing aliases ahead of time.
• Receive mail to legacy addresses. Old employee left, their firstname.lastname@yourcompany.com is still in customers' address books. Catch-all means those emails still reach you.
• Test campaigns and integrations by sending to any address that fits a pattern (e.g., test-1@yourcompany.com, test-2@yourcompany.com) without provisioning each mailbox.

Reasons NOT to enable one:

• Spam can flood the catch-all. Spammers try dictionary attacks (info@, support@, admin@, webmaster@, john@, jane@...). With catch-all on, every dictionary guess that doesn't match a real mailbox lands in your catch-all instead of bouncing. This can be 100x your legitimate volume on a domain that gets even occasional spam.
• You manage aliases proactively. If you already create aliases for each use case, catch-all duplicates effort and adds spam exposure.

The right answer depends on volume tolerance. Low-traffic personal domains often work well with catch-all. High-profile business domains usually do better with explicit aliases (which can be created in bulk — see Creating and Managing Aliases).

How to enable

1. Open Domains.
2. Click on your Active domain.
3. Switch to the Connection tab.
4. Scroll to the Catch-all Inbox card.
5. Change the selection from No catch-all to Send unknown addresses to:.
6. Pick the destination — see the two destination types below.
7. Click Save Catch-all Settings.

The change is effective within ~1 minute on the mail server. New incoming mail to unknown addresses on your domain immediately starts landing in your chosen destination.

Destination type 1: Internal mailbox

This is the default and works on every plan including Nano.

• In the destination dropdown, select an existing mailbox on the same domain.
• The mailbox doesn't need a special configuration — it's just a normal mailbox that also receives catch-all mail.

What you see in the catch-all mailbox:

• The To header preserves the original address. An email sent to xyz@yourdomain.com shows up with To: xyz@yourdomain.com.
• You can filter by To address using mail rules — useful for routing different "fake" addresses into different folders. See Creating Mail Filters.

You must have at least one mailbox on the domain before you can pick one as the catch-all destination — if the dropdown is empty, go create a mailbox first.

Destination type 2: External email address (Pro / Agency)

If you're on Pro or Agency plan, you can also route catch-all mail to any external email address (your personal Gmail, another provider, a shared inbox elsewhere).

• Choose Send unknown addresses to:, then in the destination field, type a full external email address (e.g. you@gmail.com) instead of picking from the mailbox dropdown.
• Save.

This is essentially forwarding-as-catch-all. The same plan-gating applies as regular forwarding — external destinations require the forwarding feature, which is Pro/Agency-only.

If you downgrade to Starter or Nano while an external catch-all is configured:

• The setting itself is preserved in our database (so it'll resume automatically if you upgrade again).
• But it stops working immediately on downgrade — emails to unknown addresses on your domain start bouncing again.
• The Domains page will show a "Catch-all currently inactive — requires Pro/Agency" indicator.

How catch-all interacts with mailboxes and aliases

The matching order is:

1. Specific mailbox (e.g. alice@yourdomain.com matches a mailbox literally — delivered to that mailbox).
2. Alias (e.g. sales@yourdomain.com matches an alias pointing at a mailbox — delivered there).
3. Catch-all (anything not matched above — delivered to catch-all destination).

So:

• Creating an alias for sales@yourdomain.com means mail to that exact address goes to the alias target, not the catch-all.
• Creating a real mailbox at marketing@yourdomain.com means mail to that exact address goes to that mailbox, not the catch-all.
• The catch-all only fires for truly unmatched addresses.

This means you can safely have a catch-all AND specific aliases / mailboxes — they don't conflict. Specific configurations always win.

Filtering and organising catch-all mail

The catch-all mailbox receives everything, but you don't have to scroll through it all manually. Set up Mail Rules to auto-organise:

• Filter by To header to route specific "fake" addresses to specific folders. Example: emails to any *-notify@yourdomain.com go to a "Notifications" folder.
• Auto-mark spam-looking patterns as read or move to a "Likely spam" folder. Catches the worst dictionary-attack noise.
• Auto-reply to specific patterns if you want a polite "Sorry, this address isn't monitored" bounce for some legitimate-looking typos.

Spam mitigation when catch-all is on

If catch-all is letting in a lot of spam:

• First check: is your domain's DNS authentication (SPF/DKIM/DMARC) fully green? A misconfigured DMARC means TrekMail accepts more spam by default. Fix DNS first.
• Tighten DMARC from p=quarantine or p=none to p=reject. This causes our anti-spam to be more aggressive at the front door.
• Switch off catch-all and create specific aliases for the addresses you actually need. The 10-20 aliases you'd create cover 95% of legitimate use cases without exposing 100% of the dictionary.
• Use catch-all selectively — leave it off on your main domain, use it on a secondary domain for sign-ups (like mydomain.work).

What happens to existing mail when you change catch-all

• Existing emails are not affected. Switching the catch-all destination doesn't move historical mail. Old messages stay in their current mailbox.
• Disabling catch-all stops new "unknown address" delivery immediately. Bounces resume.
• Switching destination from mailbox A to mailbox B means new emails go to B; old ones stay in A.

Common mistakes