Exchange Server 2007: Renewing the self-signed certificate

Exchange Server 2007 issues itself a self-signed certificate for use with services like SMTP, IMAP, POP, IIS and UM. The certificate is issued for a period of one year.

The self-signed certificate meets an important need - securing communication for Exchange services by default. Nevertheless, one should treat these self-signed certificates as temporary. It's not recommended to use these for any client communication on an ongoing basis. For most deployments, you will end up procuring a certificate from a trusted 3rd-party CA (or perhaps an internal CA in organizations with PKI deployed).

However, should you decide to leave the self-signed certificate(s) on some servers and continue to use them, these need to be renewed - just as you would renew certificates from 3rd-party or in-house CAs.

 To renew the certificate for server e12postcard.e12labs.com, a server with CAS and HT roles installed:

Get-ExchangeCertificate -domain "e12postcard.e12labs.com" | fl

Note the services the certificate is enabled for (by default: POP, IMAP, IIS, SMTP on CAS + HT servers). Copy the thumbprint of the certificate.

Get a new certificate with a new expiration date:

Get-ExchangeCertificate -thumbprint "C5DD5B60949267AD624618D8492C4C5281FDD10F" | New-ExchangeCertificate

If the existing certificate is being used for SMTP, you will get the following prompt:

Confirm
Overwrite existing default SMTP certificate,
'C5DD5B60949267AD624618D8492C4C5281FDD10F' (expires 8/22/2008 7:20:34 AM), with certificate '3DA55740509DBA19D1A43A9C7161ED2D0B3B9E3E' (expires 1/28/2009 7:37:31 AM)?
[Y] Yes [A] Yes to All [N] No [L] No to All [S] Suspend [?] Help
(default is "Y"):

Type y to continue. A new certificate is generated.

Thumbprint   Services   Subject
----------   --------   -------
3DA55740509DBA19D1A43A9C7161ED2D0B3B9E3E   .....   CN=E12Postcard

The new certificate is generated and enabled. Examine the new certificate:

Get-ExchangeCertificate -thumbprint "3DA55740509DBA19D1A43A9C7161ED2D0B3B9E3E" | fl

 The old certificate is enabled for IIS, POP, IMAP and SMTP. The new certificate generated using the above command is enabled only for POP, IMAP and SMTP - IIS is missing.

To enable the certificate for IIS:

Enable-ExchangeCertificate -thumbprint "3DA55740509DBA19D1A43A9C7161ED2D0B3B9E3E" -services IIS

This enables the certificate for IIS (in addition to any other services it may already be enabled for - it adds to existing values of the services property).

 Test services are working with the new certificate. If it works as expected, the old certificate can be removed:

Remove-ExchangeCertificate -thumbprint "C5DD5B60949267AD624618D8492C4C5281FDD10F"

Related posts:
- Outlook Anywhere and Exchange's Self-Signed Certificate
- Which name should I use as Common Name for my UC certificate?
- DigiCert: A Certificate Authority with excellent customer service

InsideMicrosoft: Windows Mobile 7 To Focus On Touch and Motion Gestures

I haven't written much about the exciting new developments with Windows Mobile, and the high expectations with it. Without a doubt, the iPhone has raised the bar a few notches, with typical Apple design finesse and consumer orientation (Yes, still no EAS, and still tethered to a really slow data network!). If you've been waiting to find out how Microsoft and Windows Mobile will respond to it, InsideMicrosoft has some interesting details and plenty of screenshots.

Purportedly from an internal Microsoft doc, so it's not really official, but the detailed descriptions and abundant visuals do appear quite real. Nathan Weinberg points out "the document appears to be from last summer".

More in: "Exclusive: Windows Mobile 7 To Focus On Touch and Motion Gestures"

Assigning SCL to messages scanned by 3rd-party antispam filters

Here's a problem I had a hard time resolving on Exchange Server 2003. Exchange Server 2007's Transport Rules resolve this within minutes.

Pretend you're taking a Microsoft exam:
Scenario: "You are the Exchange administrator for your organization... ".

Exchange has the Content Filter Agent (CFA), and the Edge Transport Server role designed to be a non-domain-joined mail gateway, located in perimeter networks. However, the Unix/Linux/Security folks in your organization don't trust Exchange to do the filtering (or act as the mail gateway). They insist on using open source anti-spam software, such as SpamAssasin (yes Eric, I remember CRM114 - the Controllable Regex Mutilator... and all the cool stuff you can command it to do. Just to set the record straight, I was suitably impressed back then, and continue to be so till this day.. :) on the non-Exchange SMTP gateways. After tweaking it for a number of weeks, they are able to make it work the way they want it to, or are close to it. It's implementation time!

Their solution is to insert an X-header in messages that looks like this:

X-Spam-Status:yes

That's it. Their job ends there.

As the Exchange team/administrator, your job is to ensure messages with that header end up in users' Junk Mail folder.

Exchange Server 2003 did not provide any way, out-of-the-box, to be able to inspect message headers and stamp SCL. To add some contextual fun - back then, our "solution" was a doc that showed the end-users how to create an Outlook rule to move such messages to Junk Mail. Only if Exchange/Windows admins could code... I can hear you think.

 Creating a Transport Rule: Exchange Server 2007's Transport Rules functionality allows you to accomplish this easily. Here's how:
1. Fire up EMC | Organization Config | Hub Transport | Transport Rules tab
2. Click on New Transport Rule in the Action pane
3. Give the new rule a name, add a comment if you wish
4. In the Conditions page, select the condition when a message header contains specific words
5. In the Step 2 edit box, click on the message header link

6. Type X-Spam-Status | click OK
7. In the edit box, click on the specific words link
8. Type yes | click OK | click Next
9. In the Actions page, select the action set the spam confidence level to value
10. In the rule description, click on the 0 link and add a value that's above your SCLJunkThreshold | click Next
11. On the Exceptions page, click Next if you do not want any exceptions to this rule
12. Click New | click Finish to close the wizard

Or you can use the following commands:

$condition = Get-TransportRulePredicate HeaderContains
$condition.MessageHeader = "X-Spam-Status"
$condition.words = @("yes")
$action = Get-TransportRuleAction SetSCL
$action.SCLValue = 5
new-TransportRule "Stamp SCL" -condition @($condition) -action @($action)

 Disabling the Content Filter agent: Since you have a 3rd-party filtering solution running on your non-Exchange SMTP host(s), you can disable the Content Filter Agent. Messages exceeding SCLJunkThreshold will still be moved to Junk Mail folder.

Disable-TransportAgent "Content Filter Agent"

Alternatively, you can leave the CFA enabled, but disable the Delete, Reject and Quarantine actions.

Set-ContentFilterConfig -SCLDeleteEnabled $false -SCLRejectEnabled $false -SCLQuarantineEnabled $false

Send a test message with the X-header X-Spam-Status:yes. The message has the SCL value set by the Transport Rule. If it is above the SCLJunkThreshold, it should be delivered to the Junk Mail folder.

Why this doesn't work with Delete, Reject or Quarantine thresholds enabled?

The Content Filter Agent fires on the EndOfData SMTP event. On Hub Transport servers, the Transport Rules Agent fires on the OnRoutedMessage event. If the CFA is left enabled, along with any of the above actions, messages may get deleted, rejected or quarantined. The Transport Rules Agent never gets to see deleted and rejected messages at all.

What about quarantined messages?

It's understandable if the message is already deleted or rejected - there's nothing left for the Transport Rule agent to act on! However, why doesn't the agent act on quarantined messages? With Pipeline Tracing turned on, I spent some precious cycles trying to unravel the mystery, with little success. As it turned out (thanks to helpful Exchange team folks for pointing out... ), I was overlooking the obvious - Quarantined messages are wrapped in an NDR "envelope". If you've ever logged into the quarantine mailbox and looked at quarantined messages, you know what these look like. (Related post: "HOW TO: Expose original senders and recipients of quarantined messages") The Transport Rules Agent does not see the original message headers, including our X-Spam-Status header. As a result, the rule never fires.

Life on the Edge

If using an Edge Transport server in the mix, things change. The Edge Rule agent fires on the EndOfData event, unlike Hub Transport servers. When two transport agents fire on the same SMTP event, you can set the priorities of each accordingly so one fires before the other. This is described in "How to Make the SCL Value Available to Edge Transport Rules" in Exchange Server 2007 documentation.

However, it's a lot simpler to just disable the Content Filter Agent. This meets the requirements of this scenario, where anti-spam filtering is done by 3rd-party anti-spam filters and Exchange isn't required to do any filtering at all.

The Saga Continues: White House Says It Routinely Overwrote E-Mail Tapes From 2001 to 2003

The saga of Messaging Records Mismanagement continues, with interesting bits and pieces surfacing every once in a while. Elizabeth Williamson and Dan Eggen report in the Washington Post:

From 2001 to October 2003, the White House's practice was to use the same backup tape each day...

Although the White House said in the filing that its practice of recording over the tapes ceased after October 2003, it added that even some e-mails transmitted through the end of 2005 might not have been fully preserved. "At this stage, this office does not know" whether additional e-mails are missing, said the affidavit filed minutes before a court-ordered deadline of midnight Tuesday night by Theresa Payton, chief information officer in the White House Office of Administration.

Not sure if the email messages that "might not have been fully preserved" are part of the 5 million missing messages reported earlier.

Read "White House Says It Routinely Overwrote E-Mail Tapes From 2001 to 2003" on WashingtonPost.com.

Rain City Guide: Seattle companies get no love

Just back from a good part of a week spent on the Microsoft campus, discussing Exchange developments - far more exciting than the new gadgets being unveiled at CES in Vegas all week. Though it rained almost every single day, and even snowed the night before I arrived, the weather wasn't really that bad, and the sun showed up on Friday morning. Back here in the Bay Area, the weather's been beautiful - it almost feels like spring's here!

Galen Ward in a blog post on the Rain City Guide, a great Seattle-area resource:

I'm no Microsoft "fanboy", but have you ever noticed that when they release some half baked project with a promising future (Microsoft Unified Communications Products) they get a log of grief ("Microsoft's Phone Ambitions Face A Winding Road"), but when Google comes out with a half baked product with a promising future (Google's "Presentations"), the media thinks it's cool and they focus on the future potential ("Google Presentations... one more step in the right direction").

The media's love affair with Google is never-ending. (As a sidenote, just noticed Google's Gmail web-based email service is still in beta... the oldest messages in my Gmail account are from 2004! What's interesting - nobody really cares, or even notices any more.)

Apple and Steve Jobs seem to get the similar favored treatment. To Apple's credit, it makes some really cool products, backed by some clever marketing and a media-savvy Jobs. It's MacWorld time, and the euphoria seems to be building up. As Jobs prepares to take the stage at Moscone Center tomorrow, speculation is rife about a new 3G iPhone and a new ultra-portable MacBook.

It's also time to speculate about ActiveSync support (read previous post: "Apple Licenses Exchange ActiveSync for the iPhone?).

SMTP Connector Myth: Messages are always routed over SMTP Connectors with more specific address spaces

An Exchange Server message routing myth forever being propagated (including by me!):

If 2 SMTP Connectors (or Send Connectors in case of Exchange Server 2007) exist, one with a more specific address space, like exchangepedia.com, and one for a more generic address space like *, messages are always routed over the Connector with the more specific address space.

Now, generally that rule of thumb works for most purposes, until you consider restrictions on Connectors. These include:
Connector Scope: (Entire) Organization, or the Routing Group (to which the Connector belongs or is homed to)
Message Size restrictions: To prevent messages over a certain size from being routed over a Connector
Delivery Restrictions: To allow/prevent messages from particular senders from being routed over a Connector (Exchange Server 2003/2000)


Figure 1: Content Restrictions on a SMTP Connector, including message size limit

Scenario:
You want to prevent users from sending messages over 100 Kb to exchangepedia.com.
- Connector1 for address space exchangepedia.com, message size restriction of 100Kb.
- Connector2 for address space *, no message size restrictions.
Result:
- Messages for exchangepedia.com recipients with a message size that is under the 100kb limit are routed over Connector1.
- Messages for exchangepedia.com recipients with a message size of over 100kb are routed over Connector2 with the generic address space of *. Connector1 with more specific address space of exchangepedia.com is never considered.

If you want to limit messages sent to exchangepedia.com to only 100kb, you cannot do it using the configuration in the above scenario.

From Exchange Server 2007 documentation:
Routing to External Domains -> Selecting the Routing Path to an External Recipient):

If more than one Send connector is configured to have an address space that meets the routing requirements for an external recipient, Exchange 2007 routing will select a single connector through which to route the message. The selected connector must meet the message size constraints. After Exchange 2007 has eliminated all connectors that have prohibitive message size restrictions, routing applies the following criteria to determine to which connector it will route:

From the list of all Send connectors and foreign connectors that are configured in the Exchange organization, it narrows the list to connectors that satisfy all the following criteria:

- In the scope for the local server
- Enabled
- With an address space that matches the recipient's e-mail domain

From the resulting list, select the connector with the most specific address space match. No matching connectors may be found.

Maybe an Exchange Server 2007 change, you wonder. Not quiet - Exchange Server 2003 behaves similarly.

From Exchange Server 2003 documentation:
Exchange Server 2003 Message Routing -> Routing Path Selection Process

It determines all connectors to the message destination in the organization topology, and then analyzes message characteristics and connector restrictions to exclude all those connectors that must not be used to transfer the message.

In a nutshell: Connector selection happens after restrictions are checked.

Which Connector? Determining the Send Connector used in Exchange Server 2007 is quiet easy - if using different fqdns on a Send Connector, you can simply check the Received headers; or you can look at the SMTP logs (read previous post "Exchange Server 2007: Logging SMTP Protocol Activity"). In Exchange Server 2003, you can bump up the diagnostics logging on MSExchangeTransport -> Routing Engine/Service. Exchange logs Event ID 984, which provides details about message routing, including the Connector selected.

In the following screenshots, we see 2 different SMTP Connectors being selected for 2 messages to the same destination - the smaller message uses the Connector with the specific address space - exchangepedia.com, which routes the message to a smarthost. The larger message that exceeds that Connector's message size limit is routed using the Connector for address space *, which routes the message using DNS to lookup the MX record(s) for exchangepedia.com.


Figure 2: With Diagnostics Logging enabled, Exchange Server 2003 logs Event ID 984, which shows Connector selected (for a small message under 100kb in this case). The message is delivered to the Smarthost specified in the Connector.


Figure 3: Event ID 984 shows the Connector for generic address space * selected for a larger message (over 100kb in this case). Message is delivered using DNS lookup.

Unintended consequences? The implications aren't pretty, specially when you consider scenarios where one uses a SMTP Connector for a particular address space to enforce TLS (perhaps one of the biggest reasons why messages should never be routed over a Connector with a generic address space if a Connector for a specific address space exists). If I enforce message size restrictions on my Connector with TLS enabled, larger messages can and will be transmitted using the generic Connector that does not use TLS. Now we have the larger message(s) traveling over potentially unsecured SMTP sessions.

What about Delivery Restrictions? For Exchange Server 2003, the same is true for Delivery Restrictions. If the Connector for exchangepedia.com has Delivery Restrictions to prevent Joe Adams from sending messages to Exchangepedia, the message routes over the generic Connector for * - effectively flushing such restrictions down the tube. Restrictions on Connectors with more generic address space are a different story - if Joe has Delivery Restrictions on the * Connector, he cannot send internet mail.

The first task of the Routing Engine/transport should be to check if Connectors with more specific address spaces are available. If it finds any, there is no reason to exclude these from the routing decision. Any restrictions on that Connector exist for a purpose - to restrict message sizes, or to prevent certain users from sending to particular domains using Delivery Restrictions. By excluding Connectors with restrictions from the routing calculation, we're saying routing the message is more important than enforcing those restrictions. As a result, by routing the message over generic Connectors, other requirements for mail delivery to that address space, such as those mentioned above and other available Connector settings, may not be applied.

Related Posts:
- HOW TO: Prevent a user from sending and receiving internet mail
- Exchange Server 2007: Setting Message Size Limits
- Masquerading SMTP Virtual Servers: Changing the fqdn and masquerade domain

Recipient Policies: Can separate policies for Email Addresses and Mailbox Manager Settings be applied?

Exchange Server 2003/2000's Recipient Policies can have settings to generate email addresses for recipients, and Mailbox Manager settings to manage mailbox content. (The Exchange Server 2007 equivalents are 1. Accepted Domains + Email Address Policies to generate email addresses, and 2. Managed Folder Mailbox Policies (with default or custom Managed Folders + Managed Content Settings) to manage mailbox content).

When creating these policies, one can either use a single policy with both types of settings, or use separate Recipient Policies for both purposes - one to generate email addresses for recipients, and other(s) with Mailbox Manager settings to manage mailbox content. The latter approach (separate policies) is more common.

Modifying an existing Recipient Policy to add Mailbox Manager settings

 An existing Recipient Policy can be modified to add/remove Mailbox Manager or Email Address settings by right-clicking the policy and selecting Change property pages.



 From the Property Pages dialog box, select the appropriate settings to be included in the Recipient Policy.

Can multiple Recipient Policies be applied to a recipient?
Yes, you can use separate policies to generate email addresses and manage mailbox content.

Scenario1: Single policy with Email Addresses and Mailbox Manager settings applied. Recipient Joe Adams is not managed by policies (in ADUC -> Joe's account properties | E-mail Addresses tab, Automatically update e-mail addresses based on recipient policy is unchecked). None of the settings - Email Addresses or Mailbox Manager, get applied to that user.

Scenario 2: Two separate Recipient Policies are applied - one with Email Addresses and the other with Mailbox Manager settings. Recipient Joe Adams is not managed by Recipient Policies. The policy with Email Address settings does not get applied to Joe. The second policy with Mailbox Manager settings does get applied.

Given the above scenarios, if you want Mailbox Manager settings to be applied to all mailbox-enabled users, including those that are not managed by Recipient Policies, it makes sense to use two separate policies for Email Addresses and Mailbox Manager settings respectively.

Exchange Server 2007 avoids these scenarios completely. The functionality of generating email addresses - Accepted Domains + Email Address Policies, is separate from the functionality of managing mailbox content, which is available through Managed Folder Mailbox Policies.

Related Posts:
1. Applying Mailbox Manager policies to a sub-folder
2. Exchange Server 2007: Why aren't Managed Content Settngs applied?
3. Applying Managed Folder Policy to more than one user
4. Managed Folders: How to apply different Managed Content Settings to Default Folders
5. Restricting Messaging Records Management to a particular message type