SUMMARY
Mail servers accept messages for recipients that have their
mailboxes hosted on the mail server itself. Any attempt to send a message
to a non-local recipient (i.e.: a recipient on a different mail
server) is called a 'relay'. It
is critical to regulate who
can send messages to others (non-local recipients) or the server will be identified as
'Open Relay'. The server is secured by configuring strict rules as to
who can use the server to relay messages to non-local recipients.
For a server connected to the Internet, the
recommended relay setting is to have "Allow relay for
authenticated senders" enabled, and leave "Allow relay for local sender
addresses" disabled. This is the default setting when MailEnable is
installed, and will make everyone who wants to send email through
the server provide a username and password.
DETAIL
To access the
SMTP Relay options, open the Administration program, expand the
Servers->Localhost->Connectors branch, right click on the SMTP icon,
select Properties from the popup menu, and select the Relay tab.
Find below an explanation of the various relay
settings.
| Allow relay for authenticated
senders |
This means
that users who try to send mail out through the server need
to enter a username and password (i.e. this option enables SMTP
authentication). To set this is different for various mail clients, but in Microsoft
Outlook Express and Microsoft Outlook for instance, this is in
account properties via the "My server requires authentication" checkbox under the
"Servers" tab. It is advisable to have this option enabled if privileged IP
ranges are not being used. |
| Allow relay for privileged IP
ranges |
This will allow users with certain IP addresses
to send email through the server. If the IP addresses of those users
who are able to send email out through the server is known, then use
this option. DO NOT select this if there is not a set a list of IP
addresses, as this may inadvertently allow everyone access. Normally this
option is not selected. |
| Allow relay for local sender
addresses |
This will allow users to send mail if their From
address has a domain that you host on MailEnable. For instance, if you
host example.com, and someone sends a mail that has their From address as
test@example.com
, the email will be sent. Unfortunately,
spammers may still abuse this by pretending they are one of your users, so
most servers will not use this option. |
MORE INFORMATION
How to test if a server is
secured from abuse (Open Relay Test): Article ME020168
Has the server been spammed through open relay?: Article ME020339
How MailEnable determines who can relay: Article ME020034 |
