I have this interesting case that when I am a visitor I am not allowed to send outgoing mail with my mail client (Mac OS X Mail 2.1.3), but I am with my iPhone (any version, including 3.1.2 October 2009). Both, over the local wireless network at the places we visit.
Disclaimer: sending and receiving mail with a net browser it not the theme of this post. That always works, from any location. I guess - since I am a known user.
Also, if I try sending mail from an iPod under these circumstances, I am neither allowed. With same mail set-up as the iPhone (iPod any version, including 3.1.2 October 2009).
At home
There, the outgoing mail server is smtp.online.no. All users of the wireless which uses that server with my name and password could set up their clients to send in my name. All machines on the net, including iPhone.
Visiting
The network at a friend we often see has smtp.bostream.nu as outgoing mail server. Since I want to send as myself, I have not asked for the friend's log-in details. So, Mail "refuses" me do send over that server, and trying to use the same set-up as at home it refuses me to send over smtp.online.no. I guess it's because the latter server knows the ip address or network provider I use, and then it knows who is sending: it's me, at home, I have paid for the connection: all is well. So, it's not Mail that "refuses", it merely reflects the outgoing mail servers' responses.
My queries
But why am I allowed to send via the visiting wireless from my iPhone (and neither iPod nor Mail)?
Observe that I have told the iPhone not to use the telephone connection by giving it a rubbish APN name - and configured the iPhone so that the telephone provider's server is second to the wifi server. I can see on the mail I this way am able to send from the iPhone that it's routed from bostream's dsl.bredbandsbolaget.se directly to my mail address's incoming server at start.no. My iPhone telephone provider does not seem to be in the expanded mail heading anywhere.
What are the (protocol) mechanisms?
Apple support discussion
I have posted a copy of this post at http://discussions.apple.com/thread.jspa?threadID=1969325&stqc=true
