It seems that an app on Apple MAC laptop can send mail through default port then alternative ports if the default one is blocked.
Is there a way too configure Outlook 2010 so it can do the same ?
Some applications go port hunting when the default (correct?) port is filtered. Mail (SMTP) is fortunately not one of them (the spam problem is bad enough as it stands). Besides, any halfway competently configured mail server will refuse to accept mail from random addresses.
If you need to send mail, find out what the mailserver behind the firewall is, and the configuration required to use it to relay mail outwards.