Leaving Messages on Server

  • Thread starter Thread starter O_v
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O_v

In general...

Does anyone know how this is works?

For instance, let's say there are five messages on a server. Outlook (or
whatever mail client) has downloaded all five previously. When Outlook
checks again does:

1. Outlook download all five messages again then sorts out the ones that
are duplicates?

2. Checks what it has already downloaded LIVE on the server as it checks?

And what does it check against? Is there a special code in each message?

Anyone know the answer to these questions? Where can I go to find out?

Cheers,

Mike Whalen
 
O_v said:
In general...

Does anyone know how this is works?

For instance, let's say there are five messages on a server. Outlook
(or whatever mail client) has downloaded all five previously. When
Outlook checks again does:

1. Outlook download all five messages again then sorts out the ones
that are duplicates?

2. Checks what it has already downloaded LIVE on the server as it
checks?

And what does it check against? Is there a special code in each
message?

Anyone know the answer to these questions? Where can I go to find out?
Click to expand...

You could read the POP protocol RFC for the definitive answer. In brief,
when a mail client connects with a POP server, it requests a count of all
the messages in the mailbox. After receiving it, the client asks the server
to generate a value for each message, called a UIDL. If a UIDL is one the
client has not seen before, the client considers the message new and
requests its download, saving the UIDL for furture reference. If the UIDL
is already on the list the client maintains, the client treats the message
as having been downloadd previously and doe not request it again. Here's a
sample of what the client and server say to each other:

list
+OK 3 messages (3455088 octets)
1 1725984
2 1726218
3 2886
..
uidl
+OK
1 tillman_10831457613613568
2 tillman_108314902873229312
3 tillman_108315443542351872
..
 
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