When you visit webmail.domain.tld does that work without any errors being added in the log.
Can you see anything in the Settings > ActiveSync section of the webmail account you use AS with?
Be careful when using domain names during account setup if you've asked the server to rewrite a URL from
www.domain.tld > domain.tld as that rewrite rule will kill any POST data. This was also causing me a problem with a POST form submission. GET worked as it could pass along the data in the URL but POST data was being lost..Another pesky issue that was easy to fix (don't use www in the form action link) that took hours to figure out