I have got an email from my partner outside of my SBS2008. I have tried to answer it, but have got this error: 553 5.1.1 Sorry, that domain isn't in my list of allowed rcpthosts I have tried to forward this mail to my colleague inside my company (on the same Exchange server), but have got the same error. Tried to delete appendices, body of the mail, tried to switch off antivirus and antispam on server (I am sending this e-mail from server directly from Outlook 2007) - still the same error. Evidently the Exchange does not like something inside the header. Can somebody help me? Thanks Vladimr

Hi Vladimir, Are you using pop/imap account in Outlook? If so, please check the following setting: Outlook | tools | Account Settings | your account | more settings | outgoing server | check the box my outgoing server requires authentication and log on to incoming mail server before sending email Then test the issue again. Please also let me know if youre using a smarthost for sending mail. Does the issue only happen on this email? Thanks, Elvis