Use SPF softfail, not (hard) fail
This is just flatly wrong:<p>&quot;One of them is that a relaying SMTP service (sometimes called a &#x27;forwarder&#x27;) will break SPF. This is known as the relaying problem.&quot;<p>If relaying is happening, and you haven&#x27;t added the relay to your SPF, then you&#x27;re wrong. There is no scenario where this is problem with SPF.<p>&quot;If the email is bounced on the SMTP level due to an SPF &#x27;hard&#x27; fail, the receiver may not perform further evaluation of the email, ignoring DKIM and DMARC.&quot;<p>Well, of course. If SPF is configured to disallow email, then further evaluation isn&#x27;t necessary. Either fix SPF, or don&#x27;t blame SPF.<p>These people are basically advocating for being OK with not configuring SPF properly. No. Just configure SPF properly.