SmtpException: Mailbox Unavailable When Sending From Web Page

If you are using the System.Net.Mail namespace to send mail from a web page and are using Exchange 2007, you may get the following error message: [SmtpException: Mailbox unavailable. The server response was: 5.7.1 Client does not have permissions to send as this sender].

My solution was to create a seperate recieve connector where the permission groups were set to Anonymous users as shown in the figure below:

Next, in the Network tab, in the list under Receive mail from remote servers… as shown in the graphic, I added the ip address of the server wanting to send mail.  Generally I place the IP address of individual web sites in there.  I also include developer machine IP’s as well if they are testing mail enabled apps.

Thats all there is to it. 

Fixing Attachment Limits With Co-existing Exchange 2007 & 2003 Servers

I got an unexpected error message from Outlook 2007 the other day when trying to send an email with a very large attachment. The error message was, “The attachment size exceeds the allowable limit.” 

I thought this was impossible because I just configured our newly installed Exchange 2007 (SP1) server to send attachments of any size.  Sure enough, as you can see in the screen shot below, the maximum send and recieve size checkboxes were cleared in the Exchange 2007 ESM, which means send and recieve any size attachment.

I did some checking around in ADSIEdit, and in the Message Delivery container, both DelivContLength and SubmissionContLength had values of blank, meaning send and recieve any size attachment. Furthermore, additional checking left me even more perplexed. I am running a clean install of Exchange 2007 on a dedicated server and it co-exists with an Exchange 2003 server on a seperate box that is being phased out. No mailboxes exist on the 2003 box anymore. And, since I am running SP1 on Exchange 2007 supposedly the RTM issue where Exchange 2003 global settings took preceedence over Exchange 2007 local settings was fixed. This is not the case.

If you introduced Exchange 2007 into your LAN to co-exist with an Exchange 2003 server to make it easier to migrate over, the installation process will set low default values for attachment sizes in your Exchange 2003 Service Manager and no matter what you do in the 2007 ESM or in ADSIEdit, those values take presedence.

To configure attachment settings that will work, you must use the Exchange 2003 ESM as shown below. Go to Global Settings->Message Delivery and then to properties and Defaults and then enter your settings.

Now your users will be able to send and recieve attachments of any size that you configure.

Exchange UCE Default Filter Level Changes

In checking my Exchange Server 2007 logs tonight, I noticed a message in the event log that concerned me. 

The Unsolicited Commercial Email default filter level has been updated. The new value is 4.   

My concern is that I have not touched the UCE filter since I set up the server and I do not know what is triggering these changes. In searching around the internet, I found the following post that indicated this is a bug in Exchange server.  Here is the relevent portion of the article: 

Changes to the gateway threshold inadvertently report that the store threshold was modified

When a change is made to the gateway threshold, the Exchange store reports that the store threshold has been modified in the event log even if it has not been modified. Following is a description of the event:

The Unsolicited Commercial Email default filter level has been updated. The new value is n.

This event is recorded because the user interface (UI) rewrites both values in Active Directory regardless of whether the store threshold value has changed. The Exchange store is notified of the change and writes the event entry.

The full link is here: http://support.microsoft.com/kb/867633