MailboxValidator has a field in our validation result which is the is_catchall that is used to indicate if the email address being validated is of the catch-all type. We have had our users asking why an email marked as a catch-all is showing as verified but actually incur a bounce when they sent an email to it. So that others can learn about this, we will explain why below.
What is a catch-all address anyway?
Let’s say you are emailing a new acquaintance called Mike Donut with the email address email@example.com but when you typed the recipient email address in your email client, you made a typo and ended up with firstname.lastname@example.org. Obviously, this means that your email will not reach the aforementioned Mike.
Typos are all too common when you type in an email address manually. Hence, the catch-all address came into being. It was meant to be the email address that receives any email sent to a non-existent email address in the system. When this feature is available and enabled, the mail server administrator has the option to redirect any emails sent to the wrong address to the correct recipient.
So, a catch-all address is a good thing, right?
It used to be a good thing but sadly like all things, some folks just like to ruin things for others. I’m talking about spammers. Once they’ve realized that they can spam people using the catch-all address, mail servers get inundated with a flood of marketing emails daily.
This is why nowadays it’s more likely that the catch-all address is used to bounce incoming spams instead. Unfortunately, the validation process will still get an indicator that the email address is valid which is the scenario our users have encountered.
Another thing to consider is that as an anti-spam measure, the sender email address might be automatically added to various spam blacklists. As an email marketer, that’s like the kiss of death for your marketing efforts.
Since all emails from a catch-all domain will show as valid, it is better for the sender to make sure that the recipient email address actually exists before sending any emails. For marketers, this means performing double opt-in whenever adding email addresses to your mailing list. Doing so will cut down the chances of you sending emails to a potential spam honeypot. If you aren’t sure, don’t send any emails to a catch-all address.