Not able to send mail out of UbuntuBox in send mail

Hi Guys..

yesterday i purchased a VPS server and installed sendmail on ubuntu 12.4 with Webmin & Apache runing webserver

problem is..

i can send mail via webmin user interface account to anybody to out side to any domain and able to recieve any mail from any domain..

Now main problem is

If i configure my outlook and send & receive mail i cont even send mails nor receive, i can only send mail via my linux VPS server..

Any help appreciated.....as i wanted to configure to my outlook and send mail via my linux vps server .

I am confused, what O/S is the email client, and is it also the server? Are you using SMTP, POP, IMAP or Exchange?

if this is still an issue ...

i am assuming that outlook is on a windows box ... it seems the outlook settings are incorrect as it should not matter -- from my experience anyways -- whether the mail server is running IMAP, POP3, SMTP or Exchange ... the lack of the ability of outlook to send and/or receive emails is almost always a settings issue (i.e., wrong mail server, wrong port, etc.) on outlook ...