Cannot send email - 550 relaying mail not allowed

[Brian Floyd]

I am able to receive email but not send. My ISP and email address are in
Australia (bigpond) but I am working in Russia using an ADSL connection to
access my email. My Russian ISP does not provide any service except internet
access. I am using Outlook 2007 and test emails work OK. I have not
installed any new programs and everything worked fine until I came to Russia
and added the ADSL connection.

 

[VanguardLH]

I am able to receive email but not send. My ISP and email address
are in
Australia (bigpond) but I am working in Russia using an ADSL
connection to
access my email. My Russian ISP does not provide any service except
internet
access. I am using Outlook 2007 and test emails work OK. I have
not
installed any new programs and everything worked fine until I came
to Russia
and added the ADSL connection.

Review the help web pages at your email provider to determine if they
require you to authenticate to their SMTP server when coming off their
domain. Many ISPs require authentication when you come from
off-domain so they know that you have permission to use their
resources.

For info on off-domain port 25 (SMTP) traffic blocked to thwart spam
from spammers or infected customers, read:

http://www.commercestreet.com/Blocking_Port_25.htm
http://help.yahoo.com/help/us/mail/pop/pop-38.html

http://www.postcastserver.com/help/Port_25_Blocking.aspx
http://www.aota.net/Troubleshooting/port25.php4
http://www.spamhaus.org/faq/answers.lasso?section=ISP Spam Issues...
http://www.findarticles.com/p/articles/mi_zdewk/is_200406/ai_ziff129473

http://www.google.com/search?q=+block++"port+25"++SMTP++spam