On Friday 07 Aug 2009, Mohan Sundaram wrote: > On Fri, Aug 7, 2009 at 11:47 AM, Ramkumar<[email protected]> wrote: > > Dear Friend, > > By default, some client place they blocked port > > 25.some client they open port 23 .In this place i decided to use > > SMTP port as 23 instead of 25 ? is it good? > > It is not just a matter of choice. Standard ports for known services > exist for a good reason. If some other MUA/MTA over which you've no > control wants to connect, it will try port 25 only for SMTP. > > IMHO, one should first question the logic behind blocking port 25. I > see no merit. It only isolates you from the world to run services in > a closed user group. If that indeed is the scenario, it does not > matter which port.
When you are working with ISPs who block *all* outgoing connections on port 25 but *allow* outgoing SMTP traffic on port 26. There is little choice that their end user customers have, that is the ISPs network policy to prevent SPAMMERS from sending out bulk mail to smtp hosts on the 'Net. Most hosting companies thus run their incoming SMTP connections on 26 to allow MUAs to send outgoing emails. Some ISPs do so on port 587 [1]. [1] The right way to do it is allow SMTP submissions on port 587 with user authentication (SASL auth being the common method) read more @ <http://tools.ietf.org/html/rfc5068> Of course, there is nothing stopping you from using any other port but it is not recommended. HTH -- Arun Khan -- Arun Khan _______________________________________________ To unsubscribe, email [email protected] with "unsubscribe <password> <address>" in the subject or body of the message. http://www.ae.iitm.ac.in/mailman/listinfo/ilugc
