Comment by nodamage

> EDIT: they absolutley should not use an autoincrementing int as a "support-chain token" though, that's a workaround they could easily do.

I checked my email archives and some (but not all) of the emails I've received from Zendesk have arbitrary alphanumeric ids in the Reply-To header instead of integers. Seems to depend on the company, perhaps this is a configuration issue?