When I first moved my email to A2 Hosting, mail to two people I communicate with frequently started bouncing. It turns out that their mail servers didn't like the fact that A2 has lots of customers, who naturally produce lots of email coming from what appears to be one source: the A2 IP address. So they took the ultra-conservative approach and blacklisted me as a possible spammer. The solution was to get a dedicated IP address from A2. The Original Green site is now 18.104.22.168. It costs a couple bucks a month, but it solved the email problem. That might sound like all downside, but it turns out that there are several benefits to hosting your website on a dedicated IP address. Here's an excellent post explaining them. Bottom line… I'm happy to have had the email problem.