If you are having trouble posting from your iPhone, iPad, Android or other smartphone or mobile device, please try switching from our Rich Text Editor to our Basic Editor. This should allow you to sidestep any compatibility issues with certain versions of certain mobile platforms.
You can make the switch directly on the side panel of your message composition page as follows:
If you make any changes on your settings page, please make sure to scroll down to the bottom of the page and click the "Save Settings" button: