Here's a bug I have not seen anybody talk about yet: Editing settings for email is completely broken, it seems like the retarded UI wants you to enter each word individually and then put punctuation in afterwards, so there are two different input fields, one for the value you're trying to edit and another one for the word that's being entered.
Whoever made that atrocious UI should be broken on the wheel!
Anyway once I was done wading though setting up the mail I could not make it work, because it seems there's only one particular smtp server configuration supported: Without TLS (wtf) and with login.
It seems the UI creates /rigol/data/email/etc/msmtprc every time it needs to send an email and then it invokes /rigol/data/email/bin/msmtp with the config file, which means that it's possible to test the email configuration using something like this:
<root@rigol>echo Test | ./msmtp -C ../etc/msmtprc
[email protected]msmtp: the server does not support authentication
msmtp: could not send mail (account default from ../etc/msmtprc)
The above error is what you get when you try to use a plain smtp server that doesn't want any authentication.
I see no way to turn off authentication via the UI.