[extra88]

* Mail email hosts are not cool with sending messages to large quantities of recipients because it looks like spamming, sending via a host that exists for sending mass email solves that.

* The Mailchimp platform provided some automation for the author when first asking people to opt-in. Presumably each message also includes an Unsubscribe link at the bottom which is less awkward to use than replying to the author, asking that they stop sending the email.

* TFA mentions Mailchimp's templates, it's not easy to create readable formatting of lengthy emails in standard email clients.

* It eliminates the possibility of screwing up and addressing the email to recipients using a line other than BCC.

[baroffoos]

Mailchimp basically is a spam company, except its "legitimate spam" because you signed up for a website once and forgot to opt out of spam letters. I could block every single email from mailchimp and I doubt I would miss anything that wasn't spam.