Keep an eye out for your email deliverability if many of your customers use Microsoft EOP (Exchange Online Protection)

[Dan_Stevens_]

Each month, we use Marketo to send a newsletter to our internal marketing team (about 110 people).  We found out that - even though the emails were being marked as delivered - about 75% didn't receive them.  After doing some investigating, we learned that updates were pushed out to those that use Microsoft EOP (a cloud-based email filtering service that helps protect organizations against spam and malware, and includes features to safeguard organizations from messaging-policy violations).

Microsoft EOP has algorithm which detects subject and type and source, it seems that if number of emails comes from same source in certain duration, it increase SCL, SCL should be below 5, if it goes above 5, it will mark as spam and push to quarantine. This is configured at service level (not at our company level). Apparently, since we sent the same email to 110 people (all with our company), EOP flagged this and sent all emails to quarantine.  EOP didn't even send a bounceback ping to Marketo.  So according to Marketo - and the reporting - all emails were delivered successfully.

This is yet another example on how deliverability can be negatively impacted when you send emails to multiple people at the same company.  And why I posted this discussion a while back:

Re: Now that ABM is such a large focus for many marketers, how are you effectively emailing everyone...

[Darrell_Alfons2]

Thanks for the heads up. I hope Marketo rolls out some easy way to stagger those sends.

[SanfordWhiteman]

The thing is, staggering throughout a single business day (which, in my experience, is what people are thinking when they think about marketing content) is somewhere between maybe-useful and useless.

When you consider a bunch of messages to be bulk (because they have the same fuzzy-matched hash, for example using the DCC algorithm) then the fact that you got 100 over the course of 8 hours vs. over 1 hour may not matter at all. Over the course of 5 days, on the other hand, it can have a real chance of helping, but that drastically changes the way you picture campaigns.