You have to be careful when using the web for submitting to modeling jobs from casting sites. The best advice I can give you is to NOT send a naked photo so bluntly and easily. Respect yourself and your body and do not flaunt it randomly. It can even turn casting directors off.
Also to send small files. No file should be over 150K. Make sure your jpeg size is adjusted to be 72 dpi. 300 is print size but print size is not a good size to email.
Also becareful and do your homework before you submit to a modeling gig you found on the internet. Research the name of the production, photographer, and ask questions before you submit. You don't want to waste your time with crap. There is a lot of crap on the internet to becareful.
I only suggest using nycastings.com and backstage.com for online casting sites.
Even there, you have to read the fine print and ask questions,don't be so desperate to submit to a modeling job that you disregard respect for yourself and your pursuits. It isn't worth it.
Focus on jobs which will only lead you to bigger and better things, not just because you are bored, want to show off, or just naive.
Be a smart model, it is the right way.