Yes, it's entirely possible. It is sent as plain text, and then interpreted by the recipient's email program, so sometimes things go wrong. The most common error happens when the email program breaks the invitation code onto two lines.

If your email program has automatically generated a link for you, don't click on it. Instead, copy and paste the entire link with the code into your browser. If a few characters get left out because they were moved onto the next line, type them in.

When I get a chance, I will upgrade the program to reduce the possibility of errors like these.

Regards,
Jonathan