how to save my file so that when I email it the image appears automatically when the email is opened by the recipient vs. it having to be downloaded first?

When I send a an email with a vector file attached created in AI to my customers for my business I want the image to open automatically rather than have to be downloaded.  I receive dozens of emails that do this every day, I just can't figure out how to create one myself.  Many people will not download a file they receive in an email for fear it is spam or a virus.  The svg format seems the best as once it is downloaded it stays open, but it still needs to be downloaded first and it is too slow.  Any ideas?  thanks for your help.