What you experienced is normal. As a general rule, the owner of
the SMTP server must be the same as the one providing your Internet
connection at that moment. For more on this policy see
http://www.postcastserver.com/help/Port_25_Blocking.aspx
The available workarounds when sending away from home are as follows:
1. Use webmail for sending (via your browser).
2. Ask your home ISP if they have a port other than '25' for SMTP. Who is your
home ISP?
3. If you use the same away-from-home connection frequently, substitute the
SMTP server belonging to that connection.
4. If you frequently send from multiple locations, get a free Gmail account,
configure it for POP access, and use it for your sending chores.
Gmail uses port 465 for SMTP, which is not blocked like port 25 is.
