Have you tried
here
Input your details as asked within the drop down boxes and see what happens, it should send you some settings via SMS. Also power off the handset and remove the SIM card and give the gold contact a wipe with a soft,dry and clean cloth. Pop the SIM back into the handset and try again to send an outgoing email.
Is it a PAYG handset or a Pay Monthly handset? If it's PAYG check you have enough credit. If Pay Monthly check Virgin haven't put a GPRS bar on your account, also check that your plan allows for mobile data, email usage and GPRS usage.
Do you have another email account you can use like Gmail? Just for testing purposes. I would like to see if it works on another email provider.
How many bars of signal do you have on your handset?