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75 Outbound SMTP: MercuryC and MercuryE
Configuring the MercuryE SMTP client module

two most commonly-used variations of the AUTH command, LOGIN and CRAM-MD5. You do
not have to worry which gets used - Mercury will automatically detect which variations are
available and choose accordingly. Your ISP will be able to tell you whether his SMTP server
supports SMTP AUTH.

Do not use CRAM-MD5 even if the smart host advertises it The most secure SMTP authen-
tication method is called CRAM-MD5 (for reasons far too arcane to cover here). Because it is
the most secure method, MercuryC will always choose to use it if the server indicates that it
is available. Unfortunately, some SMTP servers will advertise CRAM-MD5 as being available
even though the extra configuration necessary to support it has not actually been done: this
results in MercuryC attempting to authenticate using a method that will never actually work.
If the SMTP server to which you're connecting has this problem, checking this control will
tell MercuryC not to use CRAM-MD5, relying instead on much less secure methods of authen-
tication. If you have to check this control to get MercuryC to work, then the remote SMTP
smart host is badly misconfigured, and you should rant at its administrator until he or she fix-
es it.

Configuring the MercuryE SMTP client module

MercuryE is typically much easier to configure than MercuryC, since it usually derives the
information it needs to operate directly from your Windows workstation.

Poll the queue every X seconds (poll) The interval at which MercuryE 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 a value somewhat
larger than the poll time for the Mercury Core Module. For systems running on local area net-
works we recommend about 30 seconds for this setting.

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on a connection before assuming that the connection is no longer valid and aborting it.

Maximum simultaneous delivery threads This setting controls the number of messages Mer-
cury will attempt to deliver simultaneously. The larger the number you enter, the more heav-
ily loaded the system will become. In general, we recommend the default setting of 10 for
normal use. In systems with heavy mailing list usage, however, there may be considerable
value in setting it higher - for instance, to 30 or 40. You should not set this value above 100.
Note that you may end up being limited by the effectiveness of your Internet connection here
– if your Internet connection is only fast enough to support 10 simultaneous outgoing mail
delivery threads, then setting a maximum of 20 threads won’t make mail go out any faster
(indeed, it may actually slow delivery down somewhat).

Name servers If you are using a dialup connection, or if your TCP/IP settings are derived MercuryE is extremely de-
from a DHCP or similar configuration server, then MercuryE may not be able to obtain the pendent on having access
to reliable DNS services.
proper address for a name server it can use for resolving domain names from your Windows Using a flaky or slow DNS
registry. In this case, you will typically need to enter a name server address manually in this server will have a consid-
erable impact on its per-
field. You can enter several addresses,. separated by commas, and MercuryE will use them formance.
in order as required. Use standard Internet dotted IP notation for the name server addresses –
do not use domain names (for obvious reasons). Values entered in this field are used in pref-
erence to Windows registry settings, even if the registry settings are available and valid.

Session logging is a special mode in which a complete transcript of every outgoing session is
stored in a file. You provide the name of a directory, and MercuryE will create a file for each
session, with the extension .ME. Session logs can provide invaluable debugging information