This post from the Microsoft Online team is just what I needed for a Microsoft CRM email router project last week.
With the deployment of the August Service Update complete, SMTP clients can connect to Exchange Online SMTP servers and authenticate using Microsoft Online Services user credentials to send mail. The connection requires Transport Layer Security (TLS).
SMTP Relay capability allows organizations to use Exchange Online as an SMTP service for mail originating outside of the Exchange Online environment, for example SMTP-enabled applications such as fax servers.
To connect to the Microsoft Online Services SMTP server, open the SMTP client application and provide the following information:
· The fully qualified domain name (FQDN) of the Microsoft Online Services SMTP server. The FQDN will be slightly different depending on which Microsoft Online Services Data Center your organization is connected to. The server FQDNs are:
o North America Data Center: Smtp.mail.microsoftonline.com
o Europe Data Center: Smtp.mail.emea.microsoftonline.com
o Asia Pacific Data Center: Smtp.mail.apac.microsoftonline.com
· The user name and password of a Microsoft Online Services user account with an Exchange Online license.
o On most client applications, this is under “My outgoing mail server (SMTP) requires authentication” – this should be configured “Yes”, and the corresponding Microsoft Online username and password supplied.
· The SMTP port to use: 587.
o On most client applications, this is under “Server Port Numbers for Outgoing Server (SMTP)” – this should be configured to use port 587
· Make sure that Transport Layer Security (TLS) is enabled in your SMTP client.
o On most client applications, this is under “My outgoing mail server (SMTP) requires an encrypted connection (SSL)” – this should be configured “Yes”
NOTE: The FROM address must use a SMTP domain of type “Authoritative” – this can be confirmed in Microsoft Online Administration Center, under the Users - Domains tab.
Important: Remember to update the user Microsoft Online Services Account password regularly, before the password expires, or your SMTP-enable application will be unable to connect and send email. Microsoft Online Services passwords expire every 90 days.
Read the complete article @> Microsoft Online Services Team Blog : Using SMTP Relay with Exchange Online