If you use Google servers for your email, you may start getting a JavaScript error. This is cause by Google no longer supporting “less secure apps”. I have run across this several times with clients who use Microsoft Outlook. Each instance they also has IMAP, however this may apply to POP configurations too.
While I disagree that Outlook is a “less secure app”, we have to go with what Google says, not what we think.
Regardless if you are getting this pop up when trying to access your mail, the patch is easy.