Why does Gmail on iOS fail to send?pic.twitter.com/RDk2zJCE26
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
Actually, it's specifically custom domains that use Google Apps… 
Because it's iOS Mail
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.