Mailscanner, forwarding and SPF

Antony Stone Antony.Stone at
Tue Feb 21 11:56:40 UTC 2017

On Tuesday 21 February 2017 at 12:48:18, Nerk Nerk wrote:

> Dear MailScanner-fanatics,
> Currently I am facing some issues using MailScanner. Mostly, when the
> following situation is current:
> - Some domain using SPF, for example Paypal, sends a mail to a domain that
> I filter for

So, you are the destination of the MX records...

> - The domain is filtered through Mailscanner
> - The e-mail is forwarded to the destination

How does that happen?

> - The destination server is not under my control. They do SPF checking and
> reject the mail because the sending domain does not list my mailscanner IP
> as a valid sender
> Ofcourse I have thought of some solutions:
> 1- They need to whitelist the IP of my mailscanner

That would be good, considering that they've bought (?) a filtering service 
from you, and expect mail to pass through your servers on the way to theirs.

> 2- They need to turn off the SPF checks at the destination

Do they receive any direct (ie: not filtered through your servers) email?

> Both solutions however, require actions from a hosting party that I don't
> know and that is probably not willing.

So, why have they pointed their MX records at your server, if they're not 
wiling to adjust their server to match this?

> A third option:
> 3- I need to rewrite the sending domain somehow

Yes, like manay mailing lists do.

> Has anyone else come across this problem? How did you solve it?
> I am really wondering what solution commercial spam filtering services,
> such as SpamExperts for example, are using.

I can't speak for them.


Never automate fully anything that does not have a manual override capability. 
Never design anything that cannot work under degraded conditions in emergency.

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