Spfexp

You can override the default SPF explanation if you want. The explanation is the line returned to the SMTP sender when a mail is rejected at the SMTP level. You can use macro expansion. If a domain specifies its own explanation it is going to be used instead. The SMTP answer when rejecting mails will look like: 550 the expanded SPF explanation (#5.7.1) If you want the macro expansion explained look at the SPF draft.