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Spam Filter ISP with Office 365

Printed From: LogSat Software
Category: Spam Filter ISP
Forum Name: Spam Filter ISP Support
Forum Description: General support for Spam Filter ISP
Printed Date: 27 January 2022 at 8:51pm

Topic: Spam Filter ISP with Office 365
Posted By: Belvoir
Subject: Spam Filter ISP with Office 365
Date Posted: 09 July 2021 at 11:49am
Are there any special consideratiuons that I need to be aware of when using Spam Filter ISP Enterprise version when forwarding emails to an Office 365 client - I just cannot get it to work.

In the logfile, it always says "The remote host ( disconnected us, - message queued - to: zzzzzzzzzzzzzzzz@xxxxxxxxxxxx"

I'm tearing out what little hair I have left  LOL !!!!   BTW, I'm using SpamFilter for ISP v Enterprise

Thanks for your help

Tradaweb Ltd

PO Box 30

St Neots

Cambridgeshire PE19 7GF

UK" rel="nofollow -

Posted By: ik8sqi
Date Posted: 09 July 2021 at 10:02pm
Hi Belvoir,

The destination mail server where you're forwarding the emails to needs to be configured to whitelist your SpamFilter's IP address, or many emails will indeed be blocked. Here's an example.

Supposed your SpamFilter receives an email from to, and the destination SMTP server for your domain is

Google has an SPF record in the DNS that specifies which IPs/hosts are authorized to send emails from Your SpamFilter's IP is certainly not in that list of authorized IPs... So when receives an email from forwarded to it from your SpmFilter, it will reject it because your SpamFilter's IP is not authorized by google to send emails from

This is just one scenario - there could be other reasons like rate limiters that applies for example.

Roberto Franceschetti
LogSat Software

Posted By: yapadu
Date Posted: 20 July 2021 at 8:43pm
Usually Outlook would return some type of error, strange the Spamfilter is just saying it was disconnected.

You will need to grant exceptions to allow mail to the Office 365 connectors, as you will be violating SPF & DMARC rules of sending domains when you accept, process & forward mail direct to Office 365.

SPF & DMARC are designed specifically to prevent what you are doing - acting as a man in the middle.

I am a user of SF, not an employee. Use any advice offered at your own risk.

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