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Inhouse Application Mails are dropped in Junk???

Are you in a situation thinking why my internal mails are going to Junk?

You check your IMF, your gateway server and do all required changes but still end up seeing few mails dropped in Junk?

Now what you did here wasn’t a smart thing. All these mails are internal and why would you check IMF or your gateway server guarding your servers from external bodies. When you do a small research, you will know that all these mails are sent from your in-house custom application and they are never going to make it to IMF or Gateway. These are to be considered INTERNAL and why still in Junk?

It’s purely basis Outlook Junk Email Filter.

The filtering mechanism was invented by MS Research with the name as “SmartScreen” and implemented as outlfltr.dll in an Outlook box.

How Does this Outlook Filtering Mechanism works:- 

Ø Outlook calls function MSPST32! ScMsgScanForSpamContent to do scanning for each incoming email.

Ø Then pSCL calls another member function GetSCL to retrieve out the SCL.

Ø The SCL value higher that the Spam Threshold, it is marked as Spam

Ø Function ScHandleSpamMessage is called to move suspicious mail to Junk E-mail folder

Ø Function ScMsgScanForSpamContent calls into the member function Evaluate() to evaluate the email content which returns the ISmartScreenResultSCL pointer pSCL

Why mails from these applications are caught by Junk Email Filter:-
1#. The sender account is not identified as an internal account due to the custom coding of application and/or use anonymous authentication to connect.
2#. Whenever messages are received under an identity different from the sender address specified in MAIL FROM, they are not excluded from the anti-spam analysis
3#. Messages may contain images and external links, and the content and format would be changed each time.

There are other reasons but these are pretty common.

With the above reasons, it’s easier now for us to work with the application guys and change the code and see for changes. But will it make a difference, certainly- Yes. But there is no complete stop to Junk from these application sent emails, reason being is the algorithm which Outlook uses to do this filtering mechanism. And no one out here has the source code and symbol for the Evaluate and GetSCL functions in hand since the client-side spam scanning algorithm is very confidential even inside Microsoft. If this is publicly available, then spammers have easier job to do.

It’s hard to stop EACH AND EVERY mails sent from these custom applications not being dropped into Junk E-mail folder by changing something inside the application. And moreover these applications are used by different departments like Finance, Human Resource, R&D, Sales and all these applications are built by their own product groups. Asking these groups to modify their application is a pain for them but after doing so and if you still end up in getting a mail to Junk , you go crazy.

So what is the solution for this?
Get the list of application relaying mails and the sender address used by them and add the list to Safe Sender List in Outlook via GPO/Logon script to see no mails in junk from these applications.

Simplest task and easy to push in Outlook. Add the Sender address to Safe Sender Lists

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