Attachments Missing in some outbound mail from Exchange 2010

We have a new Exchange 2010 Standard Server setup and have migrated email from Microsoft BPOS. The server has been running for 5 days now and is working well except for one annoying problem. A user will send an email with an attachment to an email address that is external (not in the same domain), they will receive the email but they will either not have the attachments or the attachment will show up but show as a 1k file and when the user tries to open it, they will be prompted to save the file (it will have a strange file name like %000%000%00000%00000%000000) and can't be opened by anything.

Many external addresses can see the attachments and open them just fine. This only happens to a few people. They are on different domains so it is not just one email server that is having an issue. I can send the same attachments to the same recipient from a different address (not on the exchange 2010 server) and they will see the attachments and be able to open them.

The server has Windows Server 2008 R2 on it with Exchange 2010 Version: 14.02.0247.005.

Although not recommended, the server is a domain controller. There is no other software on the server except for backup software. I don't believe that Exchange does any sort of outbound email filtering by default but I have turned off the Exchange Spam filter for incoming email. This is the only Exchange server for this domain (all exchange roles are on this server).

The problem occurs when sending from outlook or from OWA.
It happens the same from multiple internal email addresses.

I believe that the issue must be in the way exchange is formatting the emails and some of the clients have an issue reading the attachments when in this format.

All suggestions are welcome. This is starting to become a big problem. Thank you for any help.

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issupport1Author Commented:
TG-TIS, the first link did not seem to apply. The second link you provided talked about filtering in exchange. The problem that I have is not with incoming email. It is with outgoing email with attachments to a handful of email addresses. Some external users that receive email from our internal users do not see the attachments in the email or they do see them but they cannot open them.
I have also turned off the exchange filtering functions.

Pavel NagaevLead email system administratorCommented:
Could you, please, send problem message to I have a look.
issupport1Author Commented:
I have found the solution to the problem. The email addresses that were having issues getting the attachments were added into the exchange server as contacts. In the contact properties in exchange there is an option for using MAPI Rich Text format. I changed this to never and now they are able to see the attachments and open them.


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issupport1Author Commented:
I was able to find the solution.
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