It's not just hotel rooms, either. It's hotel rooms, coffee houses,
client sites, airports, trains, and various other locations, using a
variety of connection methods, including POTS, cellular dial-up,
cellular data, packet radio, 802.11b/g, and various flavors
broadband. Each has its own ideosyncratic method of handling outbound
email, from blocking it, to transparent proxying, to allowing anything
through. And it's it largely not geeks doing this (though it was back
when notebooks and phones were both enough to give one a hernia).
Instead, it's salespeople, professors, marketing staff, executives,
students, and pretty much every other type of person you can
Most users employ an email client that routes outgoing mail through their
mail server hub. Direct mail send is not even supported with the most
widely used clients (Outlook, Outlook Express) and discouraged on most
The type of transitory connectivity you describe is precisely the type
of situation where routing through a hub becomes the most convenient
way to send.