Spam and relay mail server

[MahVincent]

Hi all,

Please tell me why mail server manual guides always suggest we should turn off relay function in mail servers in order to prevent spam attack. And please tell me the relationship between spam attack and relay function. And please me a couple of other ways of spam attacks and solutions prevent against it then.

Thanks in advance for your answer.

Mah Vincent

 

[marsd]

An open relay presents a set of problems for the administrator.

1) An open or promiscuous relay allows any client connecting to the
mail service to use the mta at that host to send mail with impunity.
A user could connect to your mail server and send mail to anyone
with any content using your domainname, address and resources.
This is obviously not what anyone wants.
There are ways to relay selectively. (access.db, compile time options)
There are organizations and an internet facility known as the rbl, that
look for open relays and blacklist them. This means mail from theses open
addresses will be dropped. This is for the safety of the internet community.
You can have your mta check with these dbs as well before accepting
or relaying mail.

2) unsolicited email can be blocked by entries in the access equivalent
db for your mail server. There are also ways to vlock more selectively
based on various tunable options and custom rulesets.

Hope this Helps.