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.