Yes, we face the exact same issue as all of the users above - not only follow up tickets are often not referring to the original subject and are completely separate cases, but also all the information from the previous ticket is being copied (such as tags, for example) - which affects the reporting in a negative way. Since there are different ways to group the tickets from one organisation or one user - this 'follow-up' functionality is a bit restrictive.

Having an option to disable 'follow-up' functionality as a whole would be great for many Zendesk users, of that I'm sure. I see it this way:

Initial ticket is getting solved (and then closed).
Customer replies to the same email.
A new ticket is being created, without the 'follow-up' mechanic.

Would such arrangement be possible to achieve?