[sl-1]

Not end to end encrypted? I'd wager most email traffic is encrypted while in transit, but of course that depends on the service providers. And it does sit unencrypted when stored.

[hunterpayne]

If you are emailing from a Yahoo address to a GMail address, I would bet it is. If it is going to some .gov address, who knows...maybe...maybe not???

[subscribed]

Easy to check if you were curious.

telnet to the mail server on the relevant port, either ssl, or TLS, or stattls.

You'll know :)