Hello. I have a problem like most of people so this is a simple thing to say at first. When sending mail out (reply,new) to recipient body is blank.-not even plain text shown in messages headersI am not sure if plain text can help this time.Outlook2003: Message was sent as HTML. Message is in sent items and its displayed correctly.Recipient:As I know they did not change anything on their system.I know it could be their fault but I don't think so. Us:We had Conficker.C problem. We cleaned our network from it and made Updates to Clients and Servers.Main server: Windows2003 SBS (was SP1) now SP2, Exchange2000 (was SP1) SP2 now. We still did not apply latest SP3 to it. Reason : I don't want any side effects after upgrade again. This one made me trouble already too much. Blank messages seem to be affecting now only some domains (10 I think).I also added them to system manager to Internet Delivery.-set plain text for them-seems not to work, I think Outlook overrides these settingsI also tried:-re installation of whole PC for certain-recreated Profile-removed anti virus protection (was NOD32) now none.-set default fonts, checked outgoing char set (default works for all, not changed)-only Outlook is installed (so there is no use Word as default html..... in outlook under Mail format)-registry fix can not be applied because it only fixes Exchange2003 (Exchange Transport FIX)-updated Outlook to SP3 - does not fix the problem-tried transport logging in outlook - did not get anything-event viewer does not report anything (I checked DIAGNOSTIC LOGGING,enabled some features but did not get anything what I could use, no error no warning)-message tracking tracked ok. sent out. can't get more details there-used wireshark for logging packets (did not find anything useful there)Outlook Communication is MAPI. We have IMAP and POP3 Enabled. But these are used for VPN users. And for Another server that downloads POP3 (Postfix+Dovecot+Fetchmail+KRB5+LDAP to AD). This one works with no problems. Alternative that I use now:For now I can say that mail goes out but I am still not 100% sure. I added a blank pop3 account that only uses SMTP server (alternative) to send mail out. User permissions:I doubt it. Everything worked before. Works now. Send On Behalf - Macro script in outlook and Send As Permission for a GROUP on a Mailbox. Last alternative:-send mail as plain text, and use attachments and hope it will work - not sure if it will be accepted-this increases work time for our users. html was used because copy/paste from IE,Firefox that isfast sent to other party.Reinstallation for Exchange: No way.