I am using SBS 2011 with Exchange 2010. On each client machine there is Mozilla Thunderbird installed with IMAP mailboxes to server IP.

I have started service Microsoft Exchange IMAP4, but it seems that I cannot access mailbox from Thunderbird

Here are the settings in Thunderbird:

Server Name:
Port: 143
Username: DOMAIN\username
Connection security: STARTTLS
Authentication method: Normal password

What am I doing wrong?


You'll have to enable IMAPS on port 993 and add your certificate to the IMAP service for SSL in the Exchange System Manager. Even beyond that, you have may to make some changes to the Thunderbird side to alleviate some problems with IMAP downloads. Out of the box, Thunderbird mated with Exchange can result in corrupted attachment/large email downloads. See here and here.

  • It was a matter of connection security and authentication method. – John Feb 20 '12 at 12:18

AFAIK, Exchange doesn't support starttls out of the box, you have to use an imap proxy. Try port 993 and SSL.

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