How to turn on/off special tag [AX-xxxxxxxx] in mail subject?

To turn off the mail subject special tag (what is it?):

1. Login with Avomaster/voadmin account.

2. At first, go to (1)Profile → (2)Admin
2. Then, go to (3)SMTP settings.
3. Make sure (4)Email Conversation is OFF.
4. Click (5)Update to save the changes.