Restricted SMTP Relay and SMTP Authentication Interaction
The following table describes the results of using restricted SMTP relay and SMTP authentication (see “SMTP Authentication” on page 64) in various combinations.
SMTP requires authentication | Restricted SMTP relay | Result |
On | Off | All mail servers must |
|
| authenticate before Mail |
|
| service accepts mail for relay. |
|
| Your local mail users must also |
|
| authenticate to send mail out. |
|
|
|
On | On | Approved mail servers can |
|
| relay without authentication. |
|
| Servers you haven’t approved |
|
| can relay after authenticating |
|
| with Mail service. |
|
|
|
Off | On | Mail service can’t be used for |
|
| open relay. Approved mail |
|
| servers can relay (without |
|
| authenticating). |
|
| Servers that you haven’t |
|
| approved can’t relay unless |
|
| they authenticate, but they can |
|
| deliver to your local mail users. |
|
| Your local mail users don’t need |
|
| to authenticate to send mail. |
|
| This is the most common |
|
| configuration. |
|
|
|
Rejecting SMTP Connections from Specific Servers
Mail service can reject unauthorized SMTP connections from hosts on a disapproved- hosts list that you create. Mail traffic from hosts on this list is denied and the SMTP connections are closed after posting a 554 SMTP connection refused error.
To reject unauthorized SMTP connections from specific servers:
1In Server Admin, select a computer in the Servers list, then select Mail.
2Click Settings.
3Select the Relay tab.
4Click the “Refuse all messages from these hosts and networks” checkbox.
5Edit the list of servers by choosing one of the following: ÂÂ Click the Add (+) button to add a host to the list.
ÂÂ Click the Remove
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Chapter 2 Mail Service Setup