Exchange 2007 Content FIlter: The Whitelist Is Here!

by Bharat Suneja on January 30, 2007

Messaging Hygiene features in Exchange Server 2003, including the Intelligent Message Filter (IMF), did not have a way to whitelist sending domains or SMTP addresses.

This is a follow up to a previous post, and one of the more popular ones on this blog— “IMF: Where’s the whitelist?“. (“IMF and whitelist” has for long been one of the most common search terms on this blog – Bharat).

Whitelists are common in most 3rd-party anti-spam tools. Adding domains or SMTP addresses of important senders like customers, vendors, or your CEO’s home email address (almost always an AOL address… :) for instance, ensures messages from these domains or addresses do not get filtered by the anti-spam filter.

Bypassed Senders and Sender Domains: The Whitelist

The good news is— Exchange Server 2007’s shiny new Content Filter Agent (or IMF v3 if you will) has whitelists! You can add SMTP addresses and domains to the Content Filter configuration, and have messages from these senders and domains bypass the Content Filter Agent. However, you need to resort to the Exchange shell (EMS) to manage it.

Use the following command o add sender SMTP addresses to the BypassedSenders list:

Set-ContentFilterConfig -BypassedSenders [email protected],[email protected]

Use the following command to whitelist the sending domain:

Set-ContentFilterConfig -BypassedSenderDomains somedomain.com,someotherdomain.com

Some whitelisting considerations

Before you start using whitelists, here are a few things you should consider:

  • SMTP headers can be spoofed easily. If spammers spoof any of the addresses or domains you whitelist, your recipients may end up getting more spam as all of it will bypass the Content Filter.
  • Use SenderID Filtering to detect and protect your mail system from header spoofing.
  • Maintaining whitelists, just as maintaining blacklists, is a manual process that imposes its own management costs.
  • Checking every inbound message against a list of whitelisted recipients imposes a performance penalty – miniscule as it may be. Use the whitelists sparingly.

Nevertheless, many IMF users have repeatedly demanded this functionality and it’s great to finally have it in what some folks call IMF v3.0.

Bypassed Recipients: The Exception List

The Content Filter can also be configured with an exception list – to not apply the filter to inbound messages for particular recipients. This can be done from the console by going to Hub Transport | Anti-spam tab | Content Filtering -> properties | Exceptions. This list is limited to a 100 recipients – you can add generic recipients that you want to exempt from the Content Filter, such as [email protected], [email protected], etc.

To add recipients to the exception list using the Exchange shell:

Set-ContentFilterConfig -BypassedRecipients [email protected],[email protected]

Related Posts:

{ 45 comments… read them below or add one }

Tom August 1, 2007 at 11:22 am

Why does Exchange 2007 suck so bad? It is half a product.

When adding people to my safe sender’s list, and writing people, and then checking the box that says “trust people I write to”, exchange 2007 keeps on sending emails to the SPAM box in Exchange.

And to add a domain whitelist, you have to do it via command shell. And so how can you easily look and find out your settings? And easily undo those at a later date?

You can’t.
Exchange 2007 is half a product and was released way way too soon.

I am no longer discussing Exch2007 with any of my customers. Maybe when MSFT releases Service Pack 3 or something, and makes it a complete product.

Come on Microsoft. You’re the richest company on the block, and your products are half-assed. This is pathetic.

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Bharat Suneja August 1, 2007 at 2:47 pm

Tom,

- When you add senders to the Safe Senders list in Microsoft Outlook, Exchange doesn’t know about it in real time or by itself. You have to enable Safelist Aggregation.

- Yes, some configuration can only be done from the shell (typically these are non-repetitive tasks e.g. at transport server/connector/Org level).

- Given the number of overall options available to granularly control a whole bunch of settings, it’s probably not possible to include everything in the console UI. For instance, look at all the recipient parameters you can set with Set-Mailbox and Set-CASMailbox commands.

- There’s no denying Exchange Server 2007, as released (RTM), has some rough edges, but the issues you’ve raised have been addressed above. There’s plenty of documentation on TechNet and other resources (including this blog) to help you navigate through this new version.

- Service Pack 1 is just around the corner, which should take care of a many issues.

- If you have more such specific issues please feel free to post here. I will be happy to respond. You can also pass on feedback directly to Microsoft.

Bharat

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Slag September 9, 2007 at 4:46 pm

I’m a little late to this debate, having only just discovered where all those emails were disappearing to!

Contrary to Tom above, I love the Powershell stuff.

I am somewhat annoyed that no mention of whitelists appears in the Exchange 12 chm file though.

Thank god I’ve discovered this blog – I’ve already been sidetracked off my initial query to a couple of other useful things.

It’s getting added to my RSS feeds (maybe even using Outlook this time!).

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Jon October 23, 2007 at 11:41 am

So slag, where are those emails disappearing to? That’s exactly what I’m searching for and what led me to this blog!

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aurora October 29, 2007 at 5:39 am

My application may help some people. I haven’t tested it with Exchange 2007 but it works with 2003. It’s still in early stages of development and looks basic but it was only intended as an internal program for my own use. Having said that, I understand how annoying it is not being able to whitelist sender addresses easily.

http://auroracode.blogspot.com

Try it, it may save you hours of work and effort! Obviously you should understand the risks of whitelisting addresses rather than IP’s but it is a requirement, for me anyway.

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csommers November 6, 2007 at 2:38 am

The trouble with Microsoft’s anti-spam solution is that it still lies in the administrators hands to manually look for the 1% of emails that are actually legitimate, in the vast sea of junk that is out there. In Exchange 2007, Microsoft has further complicated matters by putting this junk mail into an email mailbox! At least in Exchange 2003 IMF they stored it in an EML format on the gateway…

For example, because of spending 50%-60% of my day sifting through junk to catch that small percentage, I developed a Windows service using .NET 2.0 which watches the directory in which IMF puts the archived “SPAM” messages. When a message came in it opens the EML file, logs certain header information into a database (Access or SQL/SQL Express), and twice per day sends a report to all users with a clickable link to “release” those emails. Furthermore, it contains a “whitelist” AND blacklist feature that can auto-release/delete by IP, sender, receiver, SCL rating, etc. The benefit here is that users don’t have to sift through hundreds of SPAM messages rated 6 or higher (my gateway is set at 5, and user-level junk at 4) and yet not miss potentially valid email. It’s completely eliminated my SPAM administrative workload. It’s entirely up to the end-user to sift through his/her own crap and if a legit email does come through, they can release it AND create a “server-side” rule to allow it so it is never caught again. And it also cleans up after itself, never having more than x days/months stored on the server. The last part is that it’s smart; tracking those troublesome IP addresses that the RBL doesn’t catch…

It may seem to be a good idea to store the archived crap within a single mailbox, but it’s taken third party programs (such as mine)which simply had to read a ASCII EML file to now have to have an Outlook client OR use IMAP/POP3 to “fetch” the mail – further fattening up the client (my service is a 48kb executable). By chosing to store their email in a mailbox, the man-hours I’ve spent are for naught, and ensured that I won’t upgrade for a few more years as I refuse to subscribe/purchase a anti-SPAM service/product that is already provided free from Microsoft…

If you’re interested in this program (called UCEArchive), send me a message – my display name AT terminalit.com. It’s helped me out a lot.

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trafsta December 7, 2007 at 10:33 am

Anyone have any idea how to list or view all the entries in the whitelist from the management shell or elsewhere? I can live with having to add them from the management shell (can hopefully script this someway to make it easy to do so remotely), but I would like to be able to view the list as well… and also how do you remove entries from the list? hmmm…

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Champ December 13, 2007 at 11:31 am

Here is my million dollar question….
Once you actually “whitelist” in Exchange 2007. Where in the world can you find a list/history of emails and domains “whitelisted”.

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Guamaniac December 21, 2007 at 11:25 am

Hey, trafsta.

get-contentfilterconfig should give you a list of all the content filter settings on that particular Transport server.

And I know this is the simplest of features in PowerShell, but I just love the fact that you can pipe output to the clipboard:

get-contentfilterconfig | clip

and then peruse in your favorite text editor!

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Champ December 26, 2007 at 8:40 am

The problem with

get-contentfilterconfig | clip

is that it will only post the last bypassedsenders and bypassedsenderdomain

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Bharat Suneja December 26, 2007 at 9:08 am

No, it will redirect entire output from the command.

Reply

GhostDog March 9, 2008 at 5:03 pm

how do you remove entries from the list?

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Bharat Suneja March 9, 2008 at 5:26 pm

The following post shows how to add and remove single values from multivalued attributes: HOW TO Update multi-valued attributes in PowerShell

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GhostDog March 9, 2008 at 6:27 pm

OK… you can remove entries from whitelist as explained here.

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GhostDog March 9, 2008 at 6:29 pm

Thanks Bharat –

Guess I am a day late, and a dollar short!

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Anonymous April 4, 2008 at 11:01 am

This is the issue I am having. The Exchange 2007 program only remembers the last entry in the whitelist. Can this be possible? Can anyone give me an easy way, or exact command line to Add more emails in the Powershell, without deleting the last entry?

set-contentfilterconfig -BypassedSenders += [email protected]

then I ran….

set-contentfilterconfig -BypassedSenders += [email protected]

and

set-contentfilterconfig -BypassedSenders += [email protected]

The PROBLEM is now I try to see my whitelist by doing this command.

get-ContentFilterConfig | select BypassedSenders | clip (sends output to the
clipboard)

The result of the above command is only and output of user3, it forgets that
I put in addresses 1 and 2. I tried it with the += and the + command

Anyone have any ideas???

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Anonymous April 9, 2008 at 2:54 pm

It looks like you must add the entire list again (seprated by commas) each time you add a new domain

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Bharat Suneja April 9, 2008 at 3:41 pm

The way this works, as documented in HOW TO Update multi-valued attributes in PowerShell:

- Get the existing value of the property/attribute from AD and store it in a variable
- Add one or more new values using +=
- Commit updates from the variable back to AD

Reply

r0nn13 June 11, 2008 at 5:38 am

Do these BypassedSenderDomains and users override the Junk Mail filter settings within each Outlook client?

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Anonymous October 27, 2008 at 1:04 pm

I cannot understand why Microsoft would make exchange 2007 rely on command line. command line is from the 1960s!! are we going backwards here?

how am I supposed to remember all these commands?

and no confirmation after i type a command! it just goes back to the dos prompt!

this is a nightmare

one syntax error and you get a red error message

I got into windows specifically because of the GUI, and now this?

anyone know a mail server that runs on windows that uses a GUI?

I’ll switch!

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ArmadilloOnFire March 27, 2009 at 12:04 pm

Just worked out a couple minor tweaks to some of the script tactics discussed here and thought it might be handy for others, so posting it. This script will prompt for an SMTP address and append it to the current sender white list:

cd “C:\Program Files\Microsoft\Exchange Server\scripts”
$NewWLsmtp = Read-Host “Please enter the STMP address to White List and press enter”

$CurrentList = (Get-ContentFilterConfig).BypassedSenders
$CurrentList.add($NewWLsmtp)
Set-ContentFilterConfig -BypassedSenders:$CurrentList

write-host “Current White List of Senders:”
$CurrentList = (Get-ContentFilterConfig).BypassedSenders
write-host $CurrentList |fl
read-host “Press Enter to exit”

In order to expose this as a clickable icon, create a new shortcut with the following command line:

C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -PSConsoleFile “C:\Program Files\Microsoft\Exchange Server\bin\exshell.psc1″ -command AddRec2WhiteList.ps1

Cheers

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Bharat Suneja March 27, 2009 at 12:17 pm

@ArmadilloOnFire: Thanks for posting this.

As a sidenote, many of the examples here are from the early days of Exchange 2007, Exchange Shell and PowerShell in general.

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Anonymous April 4, 2009 at 1:53 pm

open exchange management shell and run the following.

at 23:00 /every:M,T,W,Th,F,S,Su cmd /c “D:\SafeList.bat”

then create a safelist.bat with

“d:\Program Files\Microsoft Command Shell\v1.0\Powershell.exe” -psconsolefile “d:\Program Files\Microsoft\Exchange Server\bin\exshell.psc1″ -command

“get-mailbox | where {$_.RecipientType -eq [Microsoft.Exchange.Data.Directory.Recipient.RecipientType]::UserMailbox } | update-safelist”

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Anonymous April 27, 2009 at 1:23 pm

I appreciate the generosity of those providing scripts, etc, but these commands are really obtuse. MS really needs to continue to develop the GUI, and stop trying to push the command shell as a feature.

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Bharat Suneja April 27, 2009 at 2:24 pm

@Anonymous April 27: The GUI v/s shell debate will never end. Clearly, both have their fans. There are some tasks for which the shell simply isn’t suited, and the GUI console is ideal.

Similarly, for many repetitive tasks, and for automation/bulk administration, the shell is invaluable, and certainly a feature worth having.

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Kaarg May 4, 2009 at 12:58 pm

Anonymous, I am sooo with you about not having a GUI for the whitelist. I don’t need to do much on our company’s Exchange box, but editing the white lists is BY FAR the most common thing I have to do. It’s almost patently ridiculous not to have it. I’ve managed to screw up our lists twice in the last year despite doing all I can to enter in the correct info. It’s very frustrating. Thank God our consultant is nice enough to do it for me. It can’t possibly be that hard or troubling to come up with something graphical.

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Vince K. September 3, 2009 at 2:17 pm

Yeah, this will work for server side junk filtering, but what about outlook junk mail filtering? I already had a transport rule set up to set the SCL (Spam Confidence Level) to 0 and outlook still put a SCL=0 message into the junk e-mail folder! Doh…..

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Vince K. September 15, 2009 at 2:02 pm

In the outlook12 adm templates, I found a setting "Specify path to Safe Senders list". I pointed it to a text file I created (with entries on each line) at \\domain\netlogon\safesenders.txt. This is not all you need to do though. I also had to set the following two registry keys:
[HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Options\Mail]
"JunkMailImportLists"=dword:00000001
"JunkMailImportAppend"=dword:00000001

I created a custom adm template and set these two entries to Enabled as well as the specify path to safe senders list setting. This enabled me to whitelist email domains which I needed to exclude from client junk mail filtering by specifying them on a line in the text file in the form of "@domain.com". Unfortunately this will let actual spoofed spam through but in my organization this is more acceptable than the false positives on what they consider to be local email (when legitimate mail "from" our domain comes in from the outside – popular at higher education institutions).

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Anonymous October 27, 2009 at 3:36 am
deb November 24, 2009 at 9:04 am

Is there any way to see how the Junk Mail Agent is filtering?? Legitimate e-mails from our own Domain are ending up in Junk Mail folders!! I should not have to whitelist my own Exchange Domain!!

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Bharat Suneja November 24, 2009 at 10:17 am

@deb: If you mean a way to determine what part of an email causes a message to have a particular SCL score? I'm afraid not.

However, you can determine why your internal mail is being scanned.
1. Is mail submitted by authenticated senders? If yes, this isn't scanned by default. Check content filter config it it's been accidentally configured to scan authenticated mail.
2. If mail is being submitted by a trusted internal host such as an application server or copier/scanner, you can create a Receive Connector scoped to that host's IP address and bypass antispam.
3. Any hosts that handle inbound internet mail before Exchange must be added to internal SMTP servers list. See Exchange Server 2007: Making SenderID work with non-Exchange smtp hosts and Telling Exchange about (non-Exchange) SMTP servers

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Dave January 12, 2010 at 10:55 am

Can I whitelist a partner's IP address? I'd rather not whitelist the domain as it can be spoofed. I haven't heard of IP spoofing, but I guess anything is possible.

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Bharat Suneja January 12, 2010 at 3:51 pm

@Disco: You can add the IP address to the IP Allow List.

See How to Add IP Addresses to the IP Allow List and IP Block List.

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Montell January 29, 2010 at 8:54 am

I too have had enough of Exchange 2007. It completely sucks to have to look up oscure CLI commands for mundane tasks. If I wanted that I would get Linux box. MS's strategy seems clear to me; get rid of company Exchange admins and local Exchange servers and start using MS online service.
If Exchange doesn't get it's act together our company will go to an online service but I will do everything in my power to make sure it is not MS.
Google is loking like a good option…

Reply

Anonymous March 3, 2010 at 4:37 am

is it necesary to install anti-spam on hub srever…..Because as i have configure content filter through EMS

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Bharat Suneja March 3, 2010 at 6:06 am

@Anonymous from 3/3: No, it's not necessary to install anti-spam agents on Hub Transport if you have an Edge Transport server deployed (or if you're using a third-party anti-spam product/service). If you want to filter spam on the Hub using Exchange's built-in anti-spam features, you'll need to install the anti-spam agents.

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Lynne July 12, 2010 at 12:41 pm

Thank you! Thank you! Thank you!

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Darrell October 26, 2010 at 12:59 pm

Does anyone know if this whitelisting (in the Content Filter) works when you are using Connection Filtering? We wish to whitelist certain email addresses even if their email server IP Address appears on a real time block list (RBL). The description at http://technet.microsoft.com/en-us/library/aa997242(EXCHG.80).aspx would indicate Content Filtering never happens if the Connection Filter rejects the message. Oddly, the reverse seems also true – that if you allow a server IP address, then no Content Filtering takes place either.

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Madison January 24, 2011 at 11:30 am

Has anyone else encountered a bypassedsenderdomains list that isn’t bypassing all of the domains in it?
I have both the domain .aweber.com and all sub domains *.aweber.com listed for example but I still keep getting some emails blocked by the content filter.
550 5.2.1 Content Filter agent quarantined this message

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Noah August 23, 2011 at 8:20 am

Madison,

Did you ever find a solution for this? I am having the similar issue. I have white listed a domain and email address in that domain and I am still getting the email blocked by the DNSBL. If any Microsoft tech wishes to chime in at this point I would greatly appreciate it!

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Jerry February 16, 2011 at 7:35 pm

I have a spam server at the gateway and route all our smtp mail through it however domains like gmail, hotmail and yahoo get stuck in the queue viewer unless i route emai lvia a smarthost.
I’ve tried to whitelist these addresses etc but still no joy.

In fact i actually want to disable completely the spam filter on exchange and just let our spam filter on the gateway drop them.

Any ideas to assist?

tia

Reply

Bharat Suneja February 18, 2011 at 9:02 am

Does outbound mail get stuck in an Exchange queue? Whitelisting doesn’t help with outbound mail. Check the event logs and SMTP logs to determine why this happens.

Here’s how you can disable antispam features on Exchange:
Exchange 2007/2010: If you’re not using an Edge Transport server, antispam filters aren’t installed on Hub Transport servers. To disable, you can set the following to disabled:

Set-ContentFilterConfig -Enabled $false
Set-IPBlockListConfig -Enabled $false
Set-IPBlockListProvidersConfig -Enabled $false
Set-SenderFilterConfig -Enabled $false
Set-SenderIDConfig -Enabled $false
Set-SenderReputationConfig -Enabled $false
Set-RecipientFilterConfig -Enabled $false

You can also perform these steps from the EMC -> Organization Configuration -> Hub Transport node.

Exchange 2003: Antispam filtering is not configured by default. You can disable antispam filters on each SMTP virtual server’s properties.

Reply

shawn April 17, 2011 at 9:03 am
MI40 Scam March 6, 2013 at 9:28 pm

When I originally commented I seem to have clicked on the -Notify me when new
comments are added- checkbox and from now on whenever a comment is added I recieve four emails with
the exact same comment. Is there an easy method you
can remove me from that service? Many thanks!

Reply

Bharat Suneja March 11, 2013 at 12:22 pm

Couldn’t find your email address in the database and an email sent to you has bounced.

Reply

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