Invitations from events in the CalDAV Calendar have a random set of numbers

Symptoms

After creating an event in RoundCube on the CalDAV Calendar, and including a Participant that has their email hosted remotely, the email that is received has the invitation along with a random set of numbers like the following:

3
2
2
2
2
2

Description

When an event is created on the CalDAV Calender, an invitation is sent from the CalDAV service itself on the server. This email is intended to just be the invitation itself when a participant is added that is not hosted on the server. This email uses the iContact system on the server, which seems to be adding these numbers when processing the message from CalDAV.

We've opened an internal case for our development team to investigate this further. For reference, the case number is CPANEL-46417. Follow this article to receive an email notification when a solution is published in the product. 

Workaround

There is currently no workaround. The invitation itself is fine and able to be used, the set of numbers in the body of the message can be ignored.