Hi, I'm Robert and I'll be helping you with your computer question.
No that is not going to work.
A photo is not a mail file. A mail file is an actual email. A photo has to be attached to an email
And the extension list shows what program opens the file. Photo files are not opened by a mail program. Even the mail program itself would call another photo program to open a photo that came by email
Your photos should open with a photo program such as iphoto
From there you can send them as an email attachment
Or you can open the email program first and just drag the photo into a new email you create before sending it. OR hit the attachment icon in the email program and select the photo file you want to send