Well, i think that PDF format is the most accepted file format for every e-mail recipients, and keep in mind that if you're writing to companies, they use to have a mail program on their computers, but their computers could not be connected to internet, for some restrictions company policies, or, they don't want to download anything from Google Drive, Dropbox, etc. for security reasons.
That being said, I would upload your PDF resume to your iphone and send it as attachment to your e-mail messages.
This is only my personal opinion, Drake610.
Regards and best of luck