We have been a faithful customer of Mimecast for the past 4-5 years, and the experience has been good for us. At the time of our moving to Mimecast, Microsoft didn’t have all of the Defender for Office 365 features readily available, and we were getting bombarded with SPAM and Malware. The configuration was possible in Office 365 but it took a lot of manual intervention.

Microsoft addressed this by greatly simplifying the hardening of your Office 365 Exchange Online deployment.

This can easily be done in your tenant by opening Security.Microsoft.Com, going to Email and Collaboration, Policies and Rules, and enabling Strict Protection.

This, by default, will harden most settings and make it safer for your end users.

I’m now at the point where we go full shields up guard mode. And defend at all costs.

Even if it means a few emails bounce, I’d rather that than let things in.

Our migration away from Mimecast was very easy for us because we weren’t using advanced Archiving Features.

So really we just needed to flip back our MX Records directly to Microsoft.

What we would do is leave the connectors open in Office 365 just in case someone was caching our DNS (MX) records for a period.

This way mail flow would come from both sources at the same time.

This is what we would change our MX Records to for the MVPDays domain.

Give it about an hour or so to sync up and we should be in business and be able to view the mail flow directly into Office 365 which is shown below.

Next we need to change the outbound flow of messages to not go through Mimecast

I just deleted it.

And it just worked outbound via Office 365

With that, we were off Mimecast and directly into Office 365.

I hope you enjoyed this,