pdf files appear empty
I filled out a fillable pdf in Preview and saved it for e-mail, but when the recipient opened it, it appears blank. When I open the same file on my computer, it is completely filled out. I don't know why this happens or how to prevent it. Any suggestions?
I am using Preview 9.0 (909.17) and Sierra 10.12.4
Thank-you.
Mac mini (Late 2014), macOS Sierra (10.12.4)