[AusNOG] MimeCast

Chad Kelly chad at cpkws.com.au
Thu May 9 16:06:24 EST 2019

On 5/9/2019 12:00 PM, ausnog-request at lists.ausnog.net wrote:

> Hey All
> We?re having multiple problems with various client?s using Office 365 to Mimecast.
> We?re getting the SPF failures and DKIM failures, and emails are being rejected.  We?ve been trying to figure it out for a week, and I just noticed a Mimecast server we ping was working, and now is not working.  It?s almost like they have servers dying or something.
> I?m just now wondering if there?s some funky network issue going on between Microsoft and Mimecast, Microsoft tech support is like talking to a brick wall, and Mimecast refuse to talk to us, because we?re not the client?
> Have you guys had any weird and wonderful errors with Mimecast?

First question, is SPF and Dkim configured correctly on all domains?

You also would need to configure Mimecast to access the API so it has 
tenant access to the Office365 tenant.

You need admin access to the tenants to do any of this.

You also wouldn't be using Office365 for MX or SPF as Mimecast replaces 
all this as their system filters spam and sends the good mail through to 
Office365 once filtered.

If neither organisation will talk to you it is something your clients 
will need to sort out.

We don't have any issues with Office365 it works perfectly.


Chad Kelly
CPK Web Services
Phone 03 5273 0246
Web www.cpkws.com.au

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