embedded report to show related emails, how to match on subject?

I'm working on large sollution around project management.
Apart from all activities that happen in the QB-app there is of course a lot seperate of email going on.


I like to create an embedded report in a projectform that shows all related emails about the same project. (I'm talking about a potential of 100's of emails per project).

In the project table there is a field that creates for each project a unique projectID.
I've also created a table that has an exchange connection which reads all emails perfect.

What I want to achieve is to show all related emails for a particular project based on the fact that the projectID is written in the email subject.

I have a relationship projects (one) to emails (many) and the field projectID is the lookup field.

I have created a report on the table emails with a filter:
Subject | contains |  the value in field | Projects_ProjectID.

That doesn't work which makes after all sense as the relation between the email table to projects is still empty.
The records on both sides are not connected and are created independantly.
'assigning' each imported email to a projectID manually is due to quantity impossible.

How can still use the value in Projetc_ProjectID as a filter value in a email report?

Thanks