EOP SPF Record Now Using PTR

The above alphabet soup could be replaced with, "The Day Microsoft Stopped Hogging all the DNS lookups." First a little background: Sender Policy Framework, or SPF, is used to combat spoofing of email addresses. If you're not familiar with SPF, here's a little background information: http://www.openspf.org/Introduction 

Even if you are familiar with SPF, you may not be familiar with the fact that there is a limitation in the specification regarding how many DNS lookups may be performed. This limit is 10 DNS lookups total. According to the spec, if the number of DNS lookups required to query your SPF records exceeds 10, the MTA MUST return a PermError. Until very recently, Microsoft has pushed up against this limit by consuming 8 or 9 of the available 10 DNS lookups. A recent change has made the situation much more workable.

Read more ...

Published on September 30, 2014 at 2:45 pm | | 0 Comments

Filed under EOP, Exchange Online, Office 365, Microsoft Exchange