I just returned from 10 days in Osaka. I tried repeatedly to send email out from the program but could not connect with the server. I tried all kinds of configurations. I downloaded the program directly to the laptop (vs. the thumbdrive). Same result. Finally, I went to a public PC at an internet cafe. Same result. Just got home in NJ. Popped the thumbdrive into my PC. Worked fine. Any ideas? I just heard that Japanese ISP's are blocking file sharing. Any connection?
Odds are the ISP in Japan that you were connecting to has restricted their outgoing email port to only allow their customers the ability to send.
A common workaround is to change the outgoing email port in Thunderbird (which can be found in tools -> accounts -> Outgoing server) to 587.