xOn Thu, 7 Oct 2004, Dan Barker wrote:
You will connect to the 'net via your cellphone, a dial-up, or a wireless
network. Most likely, the ISP won't route port 25 traffic to your "home"
system's SMTP servers, so you must use the remote ISP's SMTP servers. They
have no idea who you are, and your home server has no idea from where you
might connect.
If someone implements a restrictive SPF-policy in its domain, he has to
provide a SMTP-server that is accessible all over the Internet for people
in that domain to send their emails. This means SMTP-AUTH (or
SMTP-after-POP or some other kind of authentication) and running on
the port that is designed for submitting mail to SMTP: 587. See
http://www.faqs.org/rfcs/rfc2476.html on that.
No rational ISP should filter port 587, and most common email software is
able to change port 25 to 587 in its SMTP-Settings.
Other solutions: VPN to home, use Webmail, etc.
Cheers,
Ernesto