Over the last week this has been repeatedly disabled automatically - I get the warning and final warning emails (though they don't include a reason), but the 'has been disabled' email isn't forwarded to GMail, which is really unhelpful.

I don't understand why my forward is getting disabled - there's plenty of space on my GMail, and it's not like Google servers are unreliable for uptime... I also receive plenty of messages between warnings, so the escalation seems incorrect/excessive.

Please let me know what I can do to stop this happening?