Close and Re-open your Gmail Account. Reopen your browser. Update your Browser. Disable your Browser Extensions. Clear The Cache And Cookies Of The Browser. Check for Viruses. Disable Google Labs Background Send. Use a Different Browser.
Gmail Server Error 707 is another common error that pops up when a user tries to send emails. A user will see an error message that looks like this: "Oops ... the system encountered a problem" or "There was a server error and your email was not sent". Disable the web browser add-ons if a user is using Mozilla Firefox or extensions in Google Chrome, then restart the browser.