Email forwarding is a popular feature among users who prefer a single email account for receiving emails from different email addresses that they own. However this convenience might contribute to hamper your email server’s reputation. In addition to the increased load for the server to handle when emails get rejected by your remote email account mail server (for various reasons) which get filled up in the queue, it may also get your mail server blacklisted.
Another potential problem is when the remote mail server uses SPF for validating the sender. Since email forwarding works like impersonating the sender as the receiving mail server just forwards the email to maintain the sender address, remote email servers with SPF will not allow the email to go through as the sending mail server could not be validated to the actual source details.
* Forwarding “Catch-all emails” to an external mail server should be avoided. The best solution is to set the default box to :fail: so that messages are rejected and bounced back.
* Instead of using email forwarding, create an email account instead of email forwarder address and use POP feature in your main email account (like Gmail) to retrieve those emails. Email forwarding under the same domain/server will be fine.