Had some trouble recently getting clients setup with Microsoft Exchange Online services on a mobile device. Here’s the settings that worked for me.



IPhone
——
Email: user@domain.com
Server: red001.mail.microsoftonline.com (Do no included the HTTPS:\\ portion of address)
Domain: Should be left blank
Username: user@domain.com
Password: ******** (The users BPOS/Exchange Online password)



Blackberry
——
Email account: user@domain.com
Web Access URL: https://red001.mail.microsoftonline.com/owa (be sure to include the https:// and trailing /owa)
Username: user@domain.com
Password: ******** (The users BPOS/Exchange Online password)
Mailbox Name: user (just the prefix of their email address)

Great table on the features of ActiveSync and what each client (device) can do, - Wikipedia