auto-response loop

[Lem0nHead]

does anyone know a way to avoid auto-response loop?

I mean, userA sends an E-mail to userB, and both has auto-response
so the E-mail dialog is:

userA> real message
userB> I got your message, thanks!
userA> I got your message, thanks!
userB> I got your message, thanks!
userA> I got your message, thanks!
userB> I got your message, thanks!
userA> I got your message, thanks!
...