Outlook 2007 - Messaging Interface has returned unkown error - when sending mail

Hi All,

This seems to have happened after the last upgrade(V2.5.0.23), but I get this message when I try to send an email from Outlook 2007. " The messaging interface has returned an unknown error. if problem persist restart outlook"

Any ideas what or how to fix it?

Cheer in advance!

Hi There again

Not sure if this problem is related to CSE but I eventually fixed it by creating a new profile and then attaching this profile to the old data file.

Hope that helps!

Ok I discovered errors with my .pst file, I ran the inbox repair kit and this fixed the problem. The previous step I would only do if this one does not work.

See here for details on Inbox repair Kit - http://support.microsoft.com/kb/814441



Thanks for your bug report and research. :slight_smile:

To reproduce this error we need some additional info:

  1. CSE version. (seems to be 32 bit)
  2. CSE operating mode (LSP mode or Outlook plug-in Mode)
  3. OS version.
  4. Have you been prompted by CSE to upgrade it and it was auto upgraded?
  5. Which protocols your mail accounts use and do they use SSL ?

Thanks in advance.

Regards, Eugene.

Hi Eugene,

After all my posts the only way I was able to resolve the problem was to uninstall CSE version The other methods in my posts ultiamtely did not work as the problem shortly returned.

  1. I was using CSE operating Outlook plug-in mode
  2. Vista Business 32bit SP2
  3. I was prompted to upgrade
  4. pop3 protocol and no SSL

Cheers and Thanks

I saw a similiar problem with my Windows 7 x64, Outlook 2007, CSE x32 - Outlook only mode.

I found under tools > Trust Center > Email Security > Default settings. Clicked the Settings button and found the certificate was listed but the encryption protocols were not. When I put them in, I did not have any further problems, UNTIL, i restarted outlook.

I went back and found the settings I had put in were gone. Added them back and all was well until shutdown.

I have exactly the same problem with Windows 7 x64 and Outlook 2007 in Outlook Only Mode.

If I deaktivate the “Comodo SecureEmail Core” Plugin at Outlook the problem is gone. But incoming emails are no longer decyiptet automatically.

Hey there, I am having the same problem with my machine. I load/run Outlook 2007 and attempt to send an email and get the same error message. I have uninstalled CSE and now the only way I can send or recieve email is to send it unsigned and unencrpyted. Any help would be appreciated. Thanks.

Joe Freeman

ditto on this error.

I am using Outlook 2007 on Windows 7 and the latest version of CSE.

It started happening last night after I installed additional Certs for use with my other email addresses (I wish we could have just one Cert and register multiple addresses to it).

My PST became corrupted from it and I needed to run scanpst but the problem still persists. I’ve stopped the error by setting the CSE Security Level to “Off”.

CSE is useless to me at present.

Hi Bill,

In theory you can use 1 certificate for multiple email addresses as long as the name is the same. Just set up multiple profiles for each.

There seems to be some sort of bug happening with CSE. Try running it in Network Mode which worked for me.


Nice to hear you say that Eric and you are "correct". Many bugs still which is why i need to know if more updates are planned to iron out these bugs or am i just getting frustrated and wasting my time with CSE??

Comodo seems to play ok with it's own certificates but i can't figure out why it won't see my safe-mail certificate despite it being listed in my certificate store under "other people". I've tested this several times and it won't recognize and encrypt a test email to my safe-mail account with the safe-mail certificate.

Could you open a free account and test for yourself?? - http://www.safe-mail.net/

thanks Eric.
It works ok in Network mode but I’d much prefer it in Outlook mode.
At least I now know the PST is not going to get corrupted by CSE

Hi, curlin.

Windows OS shows that it doesn’t have enough information to verify the certificate (*.crt ).

Moreover, if you try to import certificate in’ Other People store’ to send encrypted e-mails in Thunderbird , it explains that:

The reason is certificate can’t be verified and will not be imported. The certificate issuer might be unknown or untrusted, the certificate might have expired or been revoked, or the certificate might not have been approved. (Outlook Express also doesn’t want to send encrypted e-mail to [at]safe-mail account)

CSE uses the same logic for certificates and for e-mail encryption. That’s why you can not send encrypted e-mail to [at]safe-mail account.

Hey Val

Thanks for checking into that. My concern is Comodo Secure Email interacting with certificates other than their own. But i think your saying it’s a Windows thing. Any idea how to get safe-mail certificates validated or trusted??

I oberseve exactly the same issue - somehow the encryption protocols get deselected and then Comodo does not work… I use several email addresses inside Outlook. Perhaps there is problem with multimple accounts and certificates?

I am using Outlook 2010 on Windows Seven x64 (32bit office software) with the Comodo Plugin only option. Outlook kept forgetting my settings for the signing and encrption certificate in

trust center
trust center settings
e-mail security

I disabled the “Comodo Secure Email Core” and mine is now working fine.
I have comodo version: