Can receive but send by using outlook express

[mcmick]

Can receive but send by using outlook express....
In webmail can send and receive.

this is the maillog on my server.

202.xxx.xxx.xxx << is sender IP

Nov  9 16:24:26 pxxxxxx postfix/anvil[29307]: statistics: max connection rate 1/60s for (smtp:202.xxx.xxx.xxx) at Nov  9 16:21:06
Nov  9 16:24:26 pxxxxxx postfix/anvil[29307]: statistics: max connection count 1 for (smtp:202.xxx.xxx.xxx) at Nov  9 16:21:06
Nov  9 16:24:26 pxxxxxx postfix/anvil[29307]: statistics: max cache size 1 at Nov  9 16:21:06
Nov  9 16:26:20 pxxxxxx postfix/smtpd[30886]: connect from unknown[202.xxx.xxx.xxx]
Nov  9 16:26:20 pxxxxxx postfix/smtpd[30886]: lost connection after CONNECT from unknown[202.xxx.xxx.xxx]
Nov  9 16:26:20 pxxxxxx postfix/smtpd[30886]: disconnect from unknown[202.xxx.xxx.xxx]