What is a catch-all address?

A catch-all email alias is an email address that is specified to receive all messages that are addressed to an incorrect email address for a domain name. In other words, a catch-all alias will catch any email sent to a non-existent email address under your domain.

How does a catch-all address work?

Say someone sends you an email but mistyped your email address. Instead of johnsmith@yourdomain.com, the email was addressed to jonsmith@yourdomain.com.

Instead of bouncing the email back to the sender, it will store the email into the catch-all account.

A catch-all alias works well if you have a high frequency of people whom mistype your email address. These mistyped email addresses will simply be bounced to your catch-all email account. But before you think catch-all accounts are a good thing, let's take a look at the downside of a catch-all account.

Downside of catch-all aliases

Spammers often try to guess email addresses in your domain, and quite often it is done via a directory harvest attack. Spam is sent to a complied list of common usernames, in different variations. If the spam is bounced back to them, then they know the email address is invalid.

When you have a catch-all alias in place, all spam sent to your domain name will be delivered to the catch-all address. One cannot fathom the scale of spam problems. For example, Google advises against creating a catch-all alias on their Gmail service:

“The volume of incoming messages may well exceed the Gmail receiving limits, resulting in the account becoming locked or in legitimate messages being deferred, delayed or bounced.” - Google

For this very same reason, Doteasy does not support catch-all alias. The catch-all alias allows spammers to send unsolicited emails to random email addresses. This creates stress on the mail servers, slowing down the mail server's normal functionality.

So what happens when senders send an email to an invalid email address?

When a sender wants to send you an email address but mistyped your domain email address, an “undeliverable” error message will be triggered and sent back to them to notify them of the problem. This gives them a chance to double-check your email address or any typing mistakes or other possible problems. Once the problem is rectified, they can then resend the email to the correct email address.

While this process involves an error message (we know many people don't like seeing error messages), it does direct their attention to any possible problems so that it can be avoided in the future. For example, say your domain email address is jsmith@jsmith.com but a friend has mistaken that it’s j.smith@jsmith.com. Note that with the extra “.” the email addresses are no longer the same. Things will remain fine and dandy as long as your catch-all alias is in place. But once it’s removed for whatever reason, an “undeliverable” error message will be triggered – that’s where the confusion gets bigger – did you just change your email address? Have I been sending it to the wrong email address all along and you didn’t tell me?

But if you don't have a catch-all alias set up, your friend would have been sent an “undeliverable” error, allowing them to locate the problem and resend the email to the correct email address, right from the get-go.