I like that it's easy to use, you can set up rules for different types of emails (like Gmail or Outlook).
It works with all email providers out there so no problems here! Nothing really - but if your looking into something more secure than gmail this isn't what we're talking about :) We have been able send bulk messages from our website without having issues when sending mass amounts at once through any provider/email client etc., which was great because sometimes people forget they've signed-up / forgot their password in order not be spammed by us again haha :D.