Sendmail configuration

[Matt Graham]

After a long battle with technology, Deepan wrote:
> I am using sendmail via php mail function to send emails. However[, a] few 
> servers reject my mails with the error 'Sender address rejected: Domain not
> found', since mails from my server are sent as email at localhost.localdomain.
> How do I change this to a valid domain name? We only own a public IP, we 
> [don't] really have a domain name.  Is it possible to use [a bare] IP ?

If you don't have valid forward and reverse DNS for the IP you're sending 
from, a fair number of places will give you a 500-series error.  There are 
good reasons for doing that, since mail from a place that has invalid DNS is 
much more likely to be spam.  Get a domain name of some type; go through 
dyndns.org if you're small-time.  Don't neglect reverse DNS!  If "host 
deepan.example.org" gets you "1.2.3.4", but "host 1.2.3.4" 
returns "SERVFAIL", then your reverse DNS is not set.  Unset reverse DNS 
means you can't send mail to AOL and probably yahoo users.  NOTE:  forward 
and reverse DNS do not have to match, they just have to be valid names.  Lots 
of times, they don't match (yay for multiple domains on one box).

And are you really using sendmail?  Unless you're a sendmail guru (which you 
aren't) or you have one on staff (unlikely), then it's often a lot simpler to 
use postfix or exim.

-- 
   You have me mixed up with more creative ways of being stupid.
   --MegaHAL, trained on random gibberish
  My blog and resume: http://crow202.dyndns.org:8080/wordpress/
Matt G|There is no Darkness in Eternity/But only Light too dim for us to see