Office 365 SMTP Relay
June 2013
Relay
Method
Send to
rcpts in
domain
Relay to
Internet
via O365
Configuration
Requirements
Requires
Authentication
Bypasses
Anti-spam
Throttling
Limits
Licensing
Requirements
Direct Send
Yes
No (Direct
delivery
only)
Port 25; TLS
optional
No
No –
suspicious
emails may be
filtered;
custom SPF
record
recommended
None
Email sender
licensing not
required
Exchange
Online Relay
Yes
Yes
Port 587 or 25;
TLS required;
dynamic IPs
allowed
Yes (If device
does not
support this
option, you can
use on-premises
IIS SMTP relay)
Yes – for mails
destined to
your Office 365
mailboxes
10,000
recipients
per day
Can use a
standard or
shared mailbox
Exchange
Online
Protection
Relay
Yes
Yes
Port 25; TLS
optional; one
or more static
IP Addresses
are required
No
No –
suspicious
emails may be
filtered;
custom SPF
record
recommended
10,000
(outbound)
recipients
per hour
Requires
Exchange Online
Protection
licenses for each
sender; Office
365 mailboxes
have this license
http://community.office365.com/en-us/wikis/exchange/how-to-setup-an-smtp-relay-inoffice-365.aspx
http://support.microsoft.com/kb/2799338
http://support.microsoft.com/kb/2600912
http://technet.microsoft.com/en-us/library/jj723133(v=exchg.150).aspx