Denis Lagno wrote:
> $ telnet flam 25             
> Trying 192.168.0.11...
> telnet: Unable to connect to remote host: Connection refused
> 
> I have not defined any packet filtering rules.
> What should I change in sendmail.cf in order to be able to
> connect from local network?

You should change the sendmail .mc file used to build the sendmail.cf file via 
m4, probably kept in /etc/mail/sendmail.mc.  Comment out the line with 
DAEMON_OPTIONS which only lists 127.0.0.1 (using "dnl ").

> Second question is about sending mail.  I used to send mail
> directly from localhost to destination mailer.  (This mail is sent
> such a way).  But some mailers reject my mail as spam.
> So I need to use some other mailer (for example free mailer)
> as authenticating relay.  How can I do this?

Use a line in the .mc file like:

define(`SMART_HOST', `your.isp.mail.server')

...which will relay the mail to your ISP's mail server.  If need be, you can 
set up SMTP AUTH to use a username/password via the access map.

www.sendmail.org has a good FAQ on this...

-- 
-Chuck