help with mail()

[eluser]Near[/eluser]
hey guys did someone knows what is this error?

Code:

SMTP server response: 530 5.7.0 Must issue a STARTTLS command first. b2sm19938569pbc.2

im using smtp.gmail.com PORT: 587

how can i fix it? TIA

by the way, we are not allowed to use any class coming from frameworks
i know this is not the right place to ask this but i realy need the answer to this..
tnx..