This article was previously published under Q270669
This article has been archived. It is offered "as is" and will no longer be updated.
The Microsoft Windows CE devices listed at the beginning of this article cannot send email through an Exchange 5.5 server when the Accept Connections: Only from hosts using: Authentication menu option is enabled in the Exchange server. The following error message is reported by the Windows CE devices:
Error sending message. Unexpected SMTP server error.
The reason for this behavior is that existing Windows CE Pocket Inbox clients do not support the security components that are required by Exchange 5.5 servers, or other SMTP servers, tovalidate them as "authenticated clients." Pocket Outlook does not support the "AUTH LOGIN" SMTP verb. Therefore, under this circumstance, the Exchange server will not forward email messages that are sent from these Windows CE devices to other mail servers.
In the Internet Mail Services Properties dialog box in Exchange 5.5, under Connections tab, there is a option to Accept Connections: Only from host using: Authentication. If this option is selected, the Windows CE devices cannot send email through the Exchange server.
To avoid the error message described in the "Symptoms" section, clear the "Accept Connections: Only from hosts using: Authentication option.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.