Without a server you can access, your only options are largely to rely on the user to copy and paste data and send it manually, but that comes with a couple issues.
- You'll probably want to encode that data to prevent the user from tampering with it, this is fine, and doable, but leads to problem 2:
- It's possible some of the data could be lost or corrupted in transition (things like certain file editors replacing characters with typographic equivalents, or the user simply failing to copy everything, etc). This will be hard to fix (probably impossible) if the data isn't human-readable.
I hate to recommend other products, but something like a Google form might be easier for this.
Another option, though, could be to have the user export their saved game and send that. Again, though, this isn't an automatic process.