(keitai-l) Sha-mail question

A quick question about @shamail - am i right in reading it thus:
The picture you send with your J-Phone to a destination that isn't on the
J-Phone network, i.e. an fixed line email address, a DoCoMo email address,
takes a week to arrive - or at least a week passes before J-Phone send the
recipient a link to the sha mail server.
And if this is so, its to encourage people to move to J-Phone? Do the other
operators' shamail services do something similar?