Email clients, such as Eudora, Outlook Express, Netscape Mail, Pine, etc., cannot access the hosted Exchange environment via the default protocol (MAPI) created by Microsoft. Instead, they must access email via POP3 or IMAP.
To setup an IMAP client for Exchange 2010
Note: If your company signed up for Exchange 2010 after 3/29/2012 then you have the Enterprise version of Exchange 2010.
SH11 Exchange 2010 Enterprise
Incoming Server Name: mail11.123together.com
Outgoing Server Name (SMTP): mail11.123together.com
Username or Account Name: your email address
SH10 Exchange 2010 Hosted
Incoming Server Name: mail10.123together.com
Outgoing Server Name (SMTP): mail10.123together.com
Username or Account Name: your email address

NOTE: To enable outgoing email, you need to tell your email client software that the outgoing server requires authentication and that it is the same as the incoming server settings. You can do this by choosing “More Settings” > Outgoing Server.
If your ISP blocks port 25 you can set your email client to communicate with our SMTP server on port 587.