Im receiving this error when trying to delete a Master-Relatioship that I don't need anymore. I already deleted all records and references to this filed in the object, but SF still trows the same error.  Any ideas?

Thanks.

​Hi everyone,

We are using a visualforce page to host buttons to create case related emails.
The problem is that the Thread ID gets expanded by 3 digits and gets added at the top of the email for no reason.
for example, it changes from [ ref:_00D30ups._50040qCn7G:ref ] to [ ref:_00D30ups._50040qCn7GAAS:ref ]

It makes the system creates a new case insead.

The email-to-case setting is set NOT to include Thread ID in Subject or body, we have this as a field in the template itself.


Any help is appreciated.