What is a catch-all email address?

When analyzing customer email subscriber lists for import into Mailchimp I always look if email addresses are catch-all (also called accept-all). Mailchimp treats these email addresses the same way that role-based email addresses are considered; low deliverability.

Catch-all email addresses are those setup to accept messages sent to any email address on a domain besides those specifically named. Say we have  the domain name example.com. We have three employees and setup email addresses for each; fiona@example.com, dave@example.com and george@example.com. But what happens if we want to setup an email address that accepts all messages not addressed to Fiona, Dave or George? We then setup a new email address and mark it as a catch-all address. Now if someone sends an email to george@example.com or dave@example.com , the message isn’t rejected by our email server or service.

Getting back to why Mailchimp deems catch-all email addresses as low deliverability; there are actually two reasons.

1. Spammers: It’s so simple for spammers to reach a person in a company when any email address to the domain will be delivered. For example, if Apple used catch-all email addresses I could sent a campaign to any name or word followed by .apple.com and the email will be delivered. Of course email list sellers can use the same principal to create subscribers to sell to unsuspecting buyers.
2. As with role-based email addresses, Mailchimp must protect its reputation and the reputation of its sending domains. If a campaign is received by a catch-all email address, there is no assurance that the person reading the campaign has agreed to receive the campaign. The receiver may then mark the message as spam which affects Mailchimp’s reputation.

Please don’t add catch-all email addresses to your Mailchimp list as they may well trigger an Omnivore warning.