I am in the same condition. This is a long lived extension, and only one developer is mantaining it, so its all about patience. If you have the time and knowledge you can collaborate with it. I would like to, but have no time or knowledge, so I cant do it right now. All I can get from the code, is that this extension is actualy an html parser, and hence everytime the provider makes a change to its interface, you will need to update the extension module.
To the people that says that webmail extension is no longer needed, well, you are partly right, but there is yet some users behind a restrictive and inflexible firewall or proxy where only the http port is allowed to be used, so imap/pop3/smtp provider ports are unusable. for those users ( like myself) this extension is important, as long as you need to use several email accounts at your workplace. you can allways go to your provider http interface, but thunderbird really rocks, and you get rid of advertisement using it, and a long etc of reasons for me.
So, I hope the extension keeps living and get it back to work soon.
sorry for my awfullenglish.