I can not send emails through "ejemplodominio.com"

[Lion uk]

Currently the service "webmail.ejemplodominio.com" with horde through works perfectly, but when I configuring outlook or any mail program, I can not send mail because it shows this error "Send test e-mail: Outlook can not connect to the outgoing mail server (SMTP). If you still receive this message, contact your server administrator or your Internet Service Provider (ISP) "·
I checked several times and settings are correct, according to the instructions of plesk, but does not work.
I can help, thanks

 

[IgorG]

Are you sure that port 25 is not firewalled somewhere between workstation with Outlook and Plesk server?

 

[Eric73]

is there a way to change port 25 for SMTP to something else within Plesk?

 

[IgorG]

is there a way to change port 25 for SMTP to something else within Plesk?

Change for what?