Sender Policy Framework (SPF) is an open standard that senders can use to publish which IPs are authorized to send email from their domain. If your mail server has an SPF check that blocks emails that fail SPF, this can cause delivery problems for senders that use SPF because email is delivered to your mail server from SpamHero's IPs.
SpamHero detects bounces caused by SPF filters and automatically re-delivers these messages using a technique that allows us to bypass the SPF filter. TLDR
For those that want to know, the technique is pretty simple... when an SPF bounce is detected, the message is re-sent to your mail server after modifying the return path to use our server's host name (the "From:" is not touched).
However, since the sender still receives a bounce, we still recommend utilizing one of the solutions below which prevent the sender from receiving a bounce.
Any of the following solutions can be used to resolve SPF delivery problems:
- Turn off the SPF check/filter on your mail server. This is the recommended solution if you are able to restrict delivery to your mail server to SpamHero IPs only. If you are using a shared email servers, this option is usually not available to you.
- Whitelist SpamHero's IPs on your mail server so that email from SpamHero is always accepted. Again, this solution is not usually possible with shared email servers.
- Enable the SPF Delivery Workaround option in the SpamHero control panel (under Settings > Filtering policies). This option is recommended when the previous two options are not possible.
A common mistake we have seen our customers make is to delete their domain's own SPF record in an effort to shut off the SPF filter for their mail server. There is no reason to delete your domain's SPF record as that will have no affect on your incoming email. Your domain's SPF record affects your outbound email only.