SSL & php

Dear all, If I use a php script in a SSL webpage I will be using a remote email address to send the incoming data (personal details, name address etc...) to... e.g. recipient@server1.com using the standard mail() function. SSL is secure for the interface between the user and the webpage and I understand that once the email has reached its destination (recipient@server1.com) it is only secure on the strength the mailbox username/password. My question is: How secure is the email in transit from the SSL page to the recipient's mailbox? Does SSL offer any security in this regard? Or does it need to be encrypted? Thanks Colm Rafferty