We had our main account which we used to send both marketing mails via MailChimp and transactional mails via SendGrid.
There also was a old account that was used by a different department for partner newsletters, which was already inactive for a few months.
They disabled the account, which we only noticed because emails stopped sending, and their UI also didn't give any explanaition. We asked their support, they said the second account was a violation of the TOS. We explained the situation and they still insisted on keeping the account closed.
Now we are with Sendgrid and are spending much less on mails, but I'd rather have lived without spending the night restoring email functionality.
