Example ticket:

> not sure what you mean by stopping forwarding

Note: We use gmail here in this example, but this pertains to any and all 3rd party mail servers, such as aol, hotmail, yahoo, etc.

Forwarding email:
bob@yourdomain.com >> bob223@gmail.com

Email sent to one of your addresses is “forwarded” to another 3rd party domain. We call these email aliases that forward mail to 3rd party servers.

Spam sent to bob@yourdomain.com is forwarded like legitimate email to bob223@gmail.com. Problem happens when gmail recognizes the spam through filtering inspections and compounded by the user bob223 when he identifies a spam message and clicks spam. This in turn tells gmail that your server is
sending out spam. Google mostly likely will first just defer your messages to give you a heads up something is wrong. But, if the amount of messages are too great, gmail will indeed permanently defer your emails, also known as blacklisting.

What happens to your mail that is forwarded if its blocked? It bounces back to the sender, which often is forged in the email reply to of the message. Spammers use this tactic in a cheap way to send out their spam. We in turn call this backscatter.

How to correct this? Simple. Remove the forwarding email address from your server’s control panel. Then, add it back specifying a user name and password to the email address. This allows you to remotely check the email direct from your server to the mail client of your choice. Mail clients can be any or a combination of the following:

• Smart phone mail app
• Computer mail client such as Microsoft or Mac Mail
• Even gmail can access your server via remote mail check (pop3/imap)

See this support article for using gmail to download your email from your server: