Working for a small not-for-profit, we were looking for an affordable alternative to MailChimp that would allow us to send out monthly emails to our networks. I started a campaign with SendinBlue and sent a test email to myself. I forwarded the test email to my manager who then took over the process and tested some of the links herself. As a result of this, our account was blocked due to "suspicious activity."
I contacted customer service and was told that they could not unblock the account because apparently, no recipient of a SendinBlue email is allowed to forward emails to others. Based on our email exchange, my understanding is that if one of our contacts forwarded an email received from our SendinBlue campaign - let's say they found it interesting and wanted to share with a colleague - then that would also be flagged and cause our account to be blocked.
Here's what they wrote: " for your subscribers to forward newsletters at their leisure to their contacts would be a violation of our opt-in policy, as those contacts did not opt-in through you directly: https://help.sendinblue.com/hc/en-us/articles/*******-Are-my-contacts-opt-in-"
After all this wasted time, I'll just stick with MailChimp.