Hi we have following problem:

we are using encrypted communication. But when there are multiple persons in the communication and we use "Reply to all" function, it ends up with "Microsoft Office Outlook had problems encrypting this message" message containing names of some recipients he cannot recognize. We have found 2 ways around:

1. Save the message to the Drafts, restart Outlook and then send the message.
2. Delete some of the recipients stated in the error message and type them again in so that Outlook recognizes them.

The additional problem is that not both work - sometimes one of them works other time the other one works. As you can see it is quite bothering. Do you have any idea how to get through this?

Additional info:

I have a new PC with Win7 Pro64 with Outlook 2010 both in Czech. There are ony few e-mails, empty Automatically filled contacts list and tidy My Contacts. Colleagues use various versions of MS Office (2003-2013; mostly 2007 and 2010). The computers are in domain. There is no MS Exchange - we use POP3/IMAP accounts on our e-mail server. Antivirus is Eset Endpoint Protection.

Thank you for your opinions.

This is not the sender's problem but the recipients who use Microsoft Office Outlook 2007. To resolve this issue, the recipient must  follow these steps:

1. On the Tools menu, click Options.
2. Click the Security tab.
3. In the Default Setting list, make sure that the correct security  profile for the digital ID that you want to use is selected.    To verify your certificate settings, click Settings.  You can click Choose, and then click View Certificate  to view your certificate details. 
4. Under Digital IDs (Certificates), click Publish to GAL, and then click OK.   This will republish the correct certificate to the global address list to make sure that users are  addressing you with the correct digital certificate.
5. Click OK when you are prompted that your certificates were published successfully.
6. Click OK to exit the Options dialog box.

More referece:

http://support.microsoft.com/kb/884738

http://support.microsoft.com/kb/980029

Tony Chen
TechNet Community Support

Thank you for your answer. However we do not use Exchange. Therefore there is no GAL I suppose. The certificates look OK.

Encrypted e-mails work well when we write to the person new e-mail or reply to his encrypted message. It does not work when we reply to multiple recipients in conversation with multiple persons in TO and CC fields.

Hi we have following problem:

we are using encrypted communication. But when there are multiple persons in the communication and we use "Reply to all" function, it ends up with "Microsoft Office Outlook had problems encrypting this message" message containing names of some recipients he cannot recognize. We have found 2 ways around:

1. Save the message to the Drafts, restart Outlook and then send the message.
2. Delete some of the recipients stated in the error message and type them again in so that Outlook recognizes them.

The additional problem is that not both work - sometimes one of them works other time the other one works. As you can see it is quite bothering. Do you have any idea how to get through this?

Additional info:

I have a new PC with Win7 Pro64 with Outlook 2010 both in Czech. There are ony few e-mails, empty Automatically filled contacts list and tidy My Contacts. Colleagues use various versions of MS Office (2003-2013; mostly 2007 and 2010). The computers are in domain. There is no MS Exchange - we use POP3/IMAP accounts on our e-mail server. Antivirus is Eset Endpoint Protection.

Thank you for your opinions.

Hello again.

We have tried this with Office 2010 and 2013 only. Outlook was using POP3/SMTP (not Kerio plugin). The problems still recurr. Do you have any idea how to proceed?

Thank you.

Hi we have following problem:

we are using encrypted communication. But when there are multiple persons in the communication and we use "Reply to all" function, it ends up with "Microsoft Office Outlook had problems encrypting this message" message containing names of some recipients he cannot recognize. We have found 2 ways around:

1. Save the message to the Drafts, restart Outlook and then send the message.
2. Delete some of the recipients stated in the error message and type them again in so that Outlook recognizes them.

The additional problem is that not both work - sometimes one of them works other time the other one works. As you can see it is quite bothering. Do you have any idea how to get through this?

Additional info:

I have a new PC with Win7 Pro64 with Outlook 2010 both in Czech. There are ony few e-mails, empty Automatically filled contacts list and tidy My Contacts. Colleagues use various versions of MS Office (2003-2013; mostly 2007 and 2010). The computers are in domain. There is no MS Exchange - we use POP3/IMAP accounts on our e-mail server. Antivirus is Eset Endpoint Protection.

Thank you for your opinions.

According to MS support, it looks like the problem is in pairing recipients addresses with the certificates stored with contacts. It seems that ESET antivirus is causing this. Turning the checking of outgoing e-mails in ESET seems to work.