Page 89 - Mercury Manual.book

The MercuryD POP3 Client Module
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Using MercuryD with Domain Mailboxes
Local user If you enter the name of a local user on your system (one to which Mercury can
delivery directly) then all the mail downloaded from the remote account will be sent to that
local user, irrespective of the address fields in the message. If you leave this field blank, Mer-
curyD will examine the To, CC and BCC fields of each message looking for addresses it rec-
ognizes as local. When it finds a local address, it will send a copy of the message to that local
user. This facility allows you to have a single mailbox (called a Domain Mailbox by most In-
ternet Service Providers) into which all mail for any users at a specified domain is placed;
MercuryD can then retrieve the mail from that mailbox and route it to the appropriate local
users for you.
Default user When distributing mail from a domain mailbox, MercuryD may encounter mes-
sages for whom it can find no local recipient; this will commonly happen if one of your users
subscribes to a mailing list, since mailing lists usually do not indicate the actual recipient an-
ywhere in the message headers. In cases such as this, MercuryD can be told to deliver the
message to a specific, or default user. If you leave this field blank, MercuryD will discard any
messages for which it can find no local delivery addresses. This field is only meaningful
when you have told MercuryD to distribute mail (by leaving the Local user field blank).
To add an account to the MercuryD service list, simply fill in the four account controls and
click the Add button. To edit an entry, click once on its entry in the list then make whatever
changes are required in the account controls and click the Change button.
Connection port and type
These controls allow you to manage the way MercuryD will connect to the POP3 server.
TCP/IP port A "port" is where MercuryD "plugs in" to the remote server when downloading
mail. The default value for this field is 110, and if you are in doubt, that is the value you
should use.
Connection type MercuryD supports internet standards called SSL and TLS, which provide
encrypted data transmission for extra security. SSL/TLS connections can be made either di-
rectly, or using a special command to switch into encrypted mode - the administrator of the
POP3 server will be able to tell you which of the two options should be used, if any. Note that
direct-connect SSL is strongly discouraged in Internet standards now: if your ISP or POP3
manager persists in using it, you should urge them to follow modern standards and change to
using user-initiated SSL instead. Note that sites using direct-connect SSL will almost always
require you to change the TCP/IP port to which you connect, usually to port 995.
Using MercuryD with Domain Mailboxes
Because of the nature of the POP3 protocol used by the MercuryD module to retrieve mail,
there will be occasions when it cannot properly identify the local recipient of a mail message
retrieved from a domain mailbox. This is because the envelope information, used to ferry the
message around the Internet, is removed once the message is placed into the destination mail-
box. Without the envelope information, MercuryD has to rely on the various From, CC, BCC
and Received headers in the message to determine the intended recipient. When one of your
users receives mail from a mailing list, his or her address may not be included in the headers
of the message: for this reason, it is usually quite important to define a "default user" for your
MercuryD Domain Mailbox entries, so that mailing list mail will be received and passed on
for manual forwarding. These problems only apply to domain mailboxes, not to mailboxes
containing mail for a single user.