socket port (25) slow responding...

Anon

Why does it take like forever to send an email when i request a mail service on port 25(smtp) through a php program? I used "fsockopen" to connect to the mail server which is on the same domain and allow relay for the web server.
In php, I open the socket once with a while loop to change "MAIL FROM:< ..>", "RCPT TO:<....>" and corresponding "DATA", so I can send several emails at once. However, it takes like forever to finish sending those emails. (Sometimes it even stuck and hang there.)
It used to work fine in this way. However, ever since I modified the "/etc/hosts" and "/etc/nsswitch.conf" on both mail server and web server, I couldn't get it back to work as before.

Pretty much confused with the need of DNS(nslookup and domain name resolve) for the type of services of TCP/IP.

Thank you for your help.

Jessica

Anon

DNS is necessary due to the anti- relaying support in sendmail. YOu mentioned that relaying is allowed for webserver. Good.

try putting the webserver's ip and fully qualified name in /etc/hosts and setting the order for 'hosts:' in nsswitch.conf to files,dns,nis (or preferrably just files,dns if you don't use NIS) This should speed things up as the nameserver (seems slow) can be bypassed for the webserver and used for all other lookups.

Spark.

Anon

Thank you for your reply.
I tried your suggestion. (in /etc/nsswitch.conf, hosts: files dns nis )
Unfortunately, it still doesn't work. "Telnet
x.x.x.x 25" seems to persist in using DNS to resolve domain name. So, would it be the wrong set up of our DNS to cause slow responding?
How do i check if our DNS is setup correctly? Currently, my ISP maintains the DNS for us, I need to identify my problem precise enough, before I can raise my complaint about it. :-P

Thank you.

Jessica