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Outbound SMTP: MercuryC and MercuryE 74
Configuring the MercuryC SMTP Client Module

tion using direct connection, tells Mercury to assume that the smart host will expect SSL en-
cryption to begin as soon as a connection is established. It is important to note that if you use
the direct connection option, you will almost certainly have to specify a different TCP port
as well (usually port 465). SSL via direct connection is heavily frowned upon these days - if
your smart host requires you to use it, you should contact the administrator and suggest that
they update to a more modern system.

Announce myself as (helo) In some situations, you may wish MercuryC to tell the servers to
which it connects that its name is something other than the value in the Core module’s Inter-
net Name for this System field. An example of a situation when this might be necessary is
when the Core Module’s name field represents an entire domain for which Mercury is acting,
but you want it to identify itself to servers using the machine’s real Internet name. In the ma-
jority of cases this field can and should be left blank.

Delivery failure template (failfile) The name and location of a template file that MercuryC
should use when reporting delivery failures. For more information on template files, see
above.

TCP/IP Timeout (timeout) the length of time in seconds that MercuryC should wait for data
on a connection before assuming that the connection is no longer valid and aborting it.

Poll the queue every X seconds (poll) The interval at which MercuryC should wake up and
see if there is any mail waiting to be delivered to the outside world. This field should not usu-
ally be set to a value less than 10 seconds, and in general should be set to some value substan-
tially larger than the poll time for the Mercury Core Module. For systems running on local
area networks we recommend about 30 seconds for this setting.

Use extended SMTP features where possible (esmtp) MercuryC understands the Extended
SMTP protocol as defined in RFC1869 and can use the SIZE extension to declare message
size to compliant servers. There should never be any need to turn this feature off – we strong-
ly recommend that you enable it unless you have specific reasons (usually a troublesome or
broken smart host) for disabling it.

Credentials for SMTP Authentication:
With the growth of malicious "spam" (unsolicited commercial junk mail) on the Internet,
many sites have begun placing restrictions on who may use their "smart" mailers to relay
mail. One of the common ways of enforcing this restriction is to require authentication of
some kind before accepting relayed mail. Mercury supports two types of authentication - au-
thentication via prior POP3 connection, and authentication via the extended SMTP AUTH
command.

With authentication via prior POP3 connection, Mercury does a simple POP3 login to a
POP3 server: if your login is successful, then the POP3 server tells the smart SMTP server
that it is OK to accept mail from your machine for a certain time (usually ten minutes or so).
Mercury can then connect normally and send mail. If your ISP uses this method to enforce
authentication, check the control labelled Authenticate via prior POP3 connection, fill in the
address of the POP3 server and put the proper POP3 username and password into the User-
name and Password fields respectively. As with the standard SMTP connection, you can
specify the port and type of connection for the POP3 connection - please see above under
Connection port/type for more information on these options.

Authentication via the extended SMTP AUTH command is handled automatically by Mercu-
ry: if you supply a username and password and have not checked the Authenticate via prior
POP3 connection control, Mercury will attempt to use AUTH instead. Mercury supports the