Most fonts come with legal licenses that restrict them from being shared. You should never upload or share a font file with a client.
Instead, convert any text in any logo design to shapes (or “outlines”) before you give the logo to your client.
This way, the client won’t need to have the font installed on their computer to be able to open the file, and your logo design will always look as great as it does on your computer.
For designs like business cards and flyers, where the client will want to be able to edit the text easily in the future, make sure the text is editable in the EPS & PDF files you supply to them. But remember to also provide the client with the details of the font you used, and tell them where they can buy it.
For more on typefaces, take a look at Typefaces: the good, the bad and the legal.
