EMAIL FORWARDING AND SENDER REWRITING SCHEME
Most email hosts including Headway allow email to be automatically forwarded to an address on another domain. Doing so may not be entirely successful though. You may have incidents of some email being rejected at the final recipient domain because of an SPF problem. SPF refers to Sender Policy Framework. SPF is one way that email hosts use to detect spam.
See: http://www.headwaysystems.com/SpamControl.html.
In summary an SPF check checks that the sender of an email is allowed to use the return address in an email, thus validating the sender. But when emails are being forwarded it can become ambiguous as to what email address is sending the message to the final recipient and what the return address should be. If the server that finally receives the forwarded message cannot validate the sender address, the message may be rejected, depending how much confidence a host puts into his SPF check.
On the Headway mail server we award some "demerit points" for the failure of an SPF check, but that check is only one of several that go into finally deciding if a message looks like spam.
For for information about email forwarding and the Sender Rewriting Scheme see the articles at:
If an email is sent to an email account that in turn is forwarding all messages to a final recipient, and the original sender gets a reply that the message is undeliverable and refers to a link such as:
then the problem is generally said to be a problem with the way that the host of the original recipient is conducting the forwarding. Furthermore, we can say that the host of the final recipient is probably being overly aggressive in the use of the SPF check when deciding if a message is spam. Headway believes that the SPF check is one check that indicates a message looks like spam, but should not be used exclusively.
If you are the owner of an email account, and you have it forwarding to another domain, and you have been told that email to the original address is being rejected because of a forwarding problem, you should pursue the issue with the host of both your email accounts. If you don't, you are losing email and will not be aware of the extent of that loss. You may be losing personal mail and business opportunities because of poor hosting practices. You should:
Tell the host of the original email account that they are not properly forwarding your messages, causing an SPF check failure at the final recipient account; and
Tell the host of the final recipient email account that they are rejecting your email by over-relying on the SPF check.
At the very least you should get your email hosts to be aware of the three articles mentioned above.
Related topics: Hosting; Spam Control.