When sending e-mail with the LabQuest 2 or LabQuest 3, the e-mail can fail to send with an error code 76. When you look at the details for that code, it will say:

msmtp: TLS handshake failed: The Diffie-Hellman prime sent by the server is not acceptable (not long enough).
msmtp: could not send mail (account default from /home/root/.msmtprc)

This happens on e-mail servers with weak encryption. The solution is to upgrade your smtp server to use stronger encryption.

You can also use a different e-mail server, such as a free Gmail account:
How do I set up LabQuest 2 to email data with a Gmail account?