Bcc: MD19-D_South_Pres-Sec it's a email address ???
you add just a CC and To you don't add BCC no ?

Correction to comment #1 Steps tp reproduce

Step 2 should have read "Select Group (distribution List from contacts and add as BCC".

I have various group with up to 60 users defined and don't want names readable. That's why I'm using BCC. Have noticed the BCC is not actally removed until message is sent. It is there in composer without the host name:
Bcc: MD19-D_South_Pres-Sec@linux-450c

ISP bounces the BCC because it cannot find a @linux-450 host. The host name is apparently added after send button in Composer is hit. I can not find a setting that says add the host name in Kmail2.

Do you have nepomuk works ?
if it doesn't work it will not find distribution list
=> will complet with machine name.

(In reply to comment #3)
> Do you have nepomuk works ?
> if it doesn't work it will not find distribution list
> => will complet with machine name.

It says its running. The file indexer, Semantic indexer and  email indexer aare all enabled. 

It is finding the distribution list when selected from Kmail2. It finds it as:
 Example: BCC: MD19-D_South_Pres-Sec 

But when the message is sent something is adding the host name:
  BCC:	MD19-D_South_Pres-Sec@linux-450c

This causes my ISP to Bounce the BCC: List.

If I can suppy additional information let me know. This was a problem back on 11.4 KDE versions, Don't remember which KDE version but think it may have 4.0 or 4.1 That was fixed.Looks like a regression.

Thanks for your help and suggestions.

Russ

Installed KDE4.8.1 release 481 from openSUSE Repo yesterday. Today I tested BCC by creatinga test group with one user in it. Either kmail or something else is adding the host name to the test group name

When the message was composed it just showed BCC: testgroup

Here's the message header after it was sent:

Code
--------
From: upscope <upscope@nwi.net>
To: russf@nwi.net
Bcc: testgroup@linux-450c
Subject: Test Message
Date: Fri, 09 Mar 2012 14:33:36 -0800
Message-ID: <2635322.QcIf86345c@linux-450c>
User-Agent: KMail/4.8.0 (Linux/3.1.9-1.4-desktop; KDE/4.8.1; x86_64; ; )
MIME-Version: 1.0
Content-Transfer-Encoding: 7Bit
Content-Type: text/plain; charset="us-ascii"
/Code
----------


openSUSE 12.1. KDE 4.8.1.

This problem originally appeared in openSUSE 11.4, not sure of KDE release but think it was 4.7. over a year ago and some update fixed it.

Just found some more info. If I just add individual contacts to an email as BCC it does not add the host name, only if I create a group in contacts and then select it as a BCC. 

Is there a unique way to create distribution groups under Contacts?

Group works with nepomuk.
If nepomuk doesn't work well for you it will not expend it and it will add hostname here.

This appears fixed in 4.8.3. I sent several emails yestrerday as BCC and they went throught. Apparently no host name was attached. I installed 4.8.4 yesteday on my other system. 
Nepomuk is enabled and running
Will make sure it still works once I'm able to send a message. Its setup exactly like this system but refuses to send mail (SMTP) but does receive mail. I'll open a new bug on that if I don't find anything.