Hi DG, On Thu, 12 Jun 2003 10:34:39 -0400 DG Raftery Sr. wrote:
>>>Can I safely run multiple email clients simultaneously, on Windows XP Pro? >> Yes. > I am going to respectively disagree. The keyword here is "simultaneously". > Two apps running a poll to a POP server(s) on port 110 would tend to confuse > the operating system. Same stands for outgoing port 25. No. Simply false. I'd be _extremely annoyed_ if my mail server couldn't be connected by multiple clients simultaneously on port 25. The same goes for Port 110 and nearly every over port a service is running on. Every service that listens on a port and does not spawn a child to handle the accepted connection for being ready to accept the next conncetion while the first still persist is either bad programmed or designed for a _VERY_ limited audience e.g. in a LAN or so. The only problem that arrises is when multiple simultaneous connections are made to a POP3 server using the same login data and therefore simultaneous access to one _Mailbox_ should be gained. But that's what locking is for: the POP3-server locks the mailbox once access is granted and every attempt to access this mailbox by a different process (resulting from a different, simultaneously opened connection) gets rejected ... until the first process releases the lock (after LOGOUT). So: should be no _general_ problem running multiple e-mail clients simultaneously, albeit "Login denied" error might occour when they try to login into the same POP3-Mailbox at (nearly) the same time. > In a nutshell two apps cannot monitor and process the same ports > "simultaneously". 1.) Not _two apps_ 2.) _monitor_ Both applies to the server. Only one app there can "LISTEN" to a specific port. But this app can spawn childs after 'ACCEPT'ing an incoming connection, with the child handling the connection and the parent continuing to LISTEN for the next one who want's to talk. On client side they don't listen nor monitor a port. Open a command line window, tell The Bat! to fetch mail and execute a 'netstat -n' in the command line while mail is fetched: the clients use upper (>1024) port for outgoing connections, two client programs connecting to port 110 one the same server use different _local_ ports. Therefore the rule of 'uniqueness' of a TCP/IP connection is kept. Uniqueness is enforced including _all_ parameters: REMOTE_IP:REMOTE_PORT<->LOCAL_IP:LOCAL_PORT As long as _one_ out of these 4 parameters differs this is a completely valid _new_ und independent connection. > If one is connected outbound to port 110 the other will > generate a "port in use" or "could not connect to server" error. Definitely wrong :-) > Sorry. Me too :-) -- Ciao, Pit ________________________________________________ Current version is 1.62r | "Using TBUDL" information: http://www.silverstones.com/thebat/TBUDLInfo.html
