how to change port 25 in smtp in zimbra mail server

[xtops]

we install zimbramail server 5.0 using ubuntu 8.04 Lts w domain name mail.emcor.com.ph ...and our client use ms outlook express to send but evry time they send mail problemm found port 25 is are blocking..but somtimes ok sometime not...not stable

[phoenix]

we install zimbramail server 5.0 using ubuntu 8.04 Lts w domain name mail.emcor.com.ph ...and our client use ms outlook express to send but evry time they send mail problemm found port 25 is are blocking..but somtimes ok sometime not...not stable

If it works occasionally then port 25 isn't being blocked, I'd suggest you most likely have a network/hardware problem. You could always relay the mail through the ISPs mail server or a paid-for service.

The user shouldn't be sending mail through port 25 on the server, you should set-up Outlook Express to use port 587 (the correct Submissions port) for sending mail, search the forums for details on hos to enable port 587 in Zimbra 5.x.