Snapcaster Mage's Flashback ability and Zeniths

[LotusHead]

If I play Snapcaster Mage, and give say, Blue Sun's Zenith flashback, then play Blue Sun's Zenith for x=1, does Zenith get shuffled back into deck?

 I think it does, because that's what Blue Sun's Zenith says to do when it resolves, but other abilities (say, buyback on capsize if I flashed it back) don't put it back in hand.

Any clarification would be helpfull.

[Clariax]

The Zenith will be exiled.  When a spell with flashback leaves the stack, if it's going to any zone other than exile, it gets exiled instead.  Why it's leaving the stack doesn't matter.