The topic of this article is supported in its entirety by our customer support department.

If you are using a shared IP address, webmail, or forwarding your email to an outside destination your email may be being rejected because the larger ISP’s (such as Comcast, Verizon, AOL, Hotmail and many others) will block the IP of the shared server your account is being hosted on.

With shared hosting/using a shared IP address, there will be several users who forward their email to their own ISP email address. The ISP then notices a lot of email coming in from the same IP address and will blacklist it. We contact them and they remove the block but email continues to forward and it happens again. You should be able to use the same settings as you do now but the problem may continue. (webmail and forwarding email will always use the shared IP address on the server)

The only way to eliminate this is to use your ISP for your outgoing/SMTP mail settings in your email client.