If you use Office 365 or other Microsoft Exchange-based email, you can add an email account from another email service (for example, Gmail, Yahoo! Mail Plus, or Comcast) as a connected account. For information about how to add a connection to another email account, see Connect to another email account.
Do you have lots of existing business contacts that you want to include in the shared address book in Exchange Online? Or add your contacts as members of distribution groups, just like you can with users inside your company? If so, you can use Windows PowerShell and a CSV (Comma Separated Value) file to bulk import external contacts into Exchange Online.
Here is what I have:
1. Office365 Wave 15 Update
2. Brother MFC-8950DW with firmware L 1.04
3. Office365 Exchange Plan 1 (Enterprise)
SMTP Server Address: smtp.office365.com
SMTP Port: 587
SMTP Server Authentication: SMTP-AUTH
SMTP-AUTH Account Name: firstname.lastname@example.org (note that the account I used is a full admin and this may be required)
SMTP-AUTH Account Password: your password here
SMTP over SSL/TLS: TLS