Sendmail

[Alexander Dalloz]

Am Di, den 12.04.2005 schrieb Temlakos um 5:11:

> It's worth asking right now: What TCP or UDP port does Sendmail use? My 
> guess is Port 25. In which case, you might as well know: a columnist 
> writing for /eWeek/ has just recommended that every ISP /deny access to 
> Port 25/ to all residential Internet accountholders. The reason: people 
> are setting up their own mail servers and using them to crank out spam. 
> When Port 25 gets blocked, Sendmail becomes useless--unless I'm missing 
> something.
> 
> Temlakos

The MTA port is port 25, correct. TCP only. You may see /etc/services
files.
And it is right that much harm comes from SMTP servers running on
dial-up lines, most are trojaned hosts, misused by spammers.
Even if ISP's block port 25 for outside/outbound connections an MTA like
Sendmail on the home PC can be handy. Then the ISP's relay host should
be used (either on port 25 or MSA port 587). Inbound mail may be fetched
from POP3/IMAP servers which are used for mailing. Running a local MTA
can help to better and easier fight against spam in your inbox.

Alexander


-- 
Alexander Dalloz | Enger, Germany | GPG http://pgp.mit.edu 0xB366A773
legal statement: http://www.uni-x.org/legal.html
Fedora Core 2 GNU/Linux on Athlon with kernel 2.6.11-1.14_FC2smp 
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