Mimecast error

Some receiving email servers are configured with a product called Mimecast.

The servers are configured to not allow specific emails to be delivered if the content does not match their requirements.

This is all about the receiving email server and how their SPAM policies have been set out, as to what information they accept via incoming email.  This is the email service that the person you are trying to send the email is using.  

Each mail server is configured to only allow certain types of emails to be received, and if an email which is trying to be received doesn’t match their configured criteria, then the email bounces.

The Mimecast Community has a website https://community.mimecast.com/docs/DOC-1369#554 which outlines the error codes.

A sample is shown below.

The error could be due to a URL in the footer of your email stationery or even an embedded picture which is not allowed to be received by the incoming server.

If you are able to send a normal email via Outlook, it may be something that is stored within your Nimbus email stationery (which may be different to the stationery you use via Outlook).

The way around this, is to ask your Client to contact their Email provider and request that they whitelist any email being sent from https://*.nimbushost.net/.