Why won't Mailchimp send to some of my subscribers?

A client recently asked why Mailchimp won’t accept certain of her subscriber email addresses even although she knows the email addresses to be valid. Here is part of my response.

In its simplest form, its important to understand why Mailchimp will or won’t accept an email address. Ultimately with Mailchimp it’s all about protecting their domains (see a list of Mailchimp sending domains). The process of validation and verification, when importing subscribers, is about determining which email addresses will either be marked as spam by a receiving email server, marked as spam by the receiving person or hard bounced (i.e. the email address no longer exists). For Mailchimp, the very worst is if the receiving server or person identified the message as spam as this negatively affects Mailchimp domain reputation. If enough messages received by Mailchimp domains are marked as spam then eventually more and more (and ultimately likely all) emails sent by Mailchimp will start to get automatically marked as spam. Should this happen then Mailchimp is effectively finished as a company.

In regards to your email addresses, even although some are legitimate email addresses and people have agreed to receive your marketing communication, the risk of Mailchimp sending to that email address is high in relation to the possibility of the receiving email server or viewer marking the message as spam. Catch all and role-based email addresses attract issues as often multiple people are checking a single email inbox and the person checking the shared email inbox may not be the person that subscribed to the email newsletter.

It’s possible that Mailchimp will accept some of the email addresses in the spreadsheet that I haven’t identified as being safe to add (and the converse is true that Mailchimp may mark some of the ones I’ve identified as safe as in-fact unsafe). The problem is that, especially at first, it’s advisable to take a cautious approach as if too many unsafe email addresses are imported then Mailchimp will first suspend and then eventually close your account. My recommendation is to be cautious at first and once you’ve been with Mailchimp for a few months then try to import further email addresses.