[AT] List attachments

[Spencer Yost]

Here is the summary of what was done today:

1 Identity of Sender Restored
2 Messages with attachments are rejected(sender is notified) 
3 Messages that are text/HTML are converted to text/plain.
4 "Acknowledgement of posting" setting is off by default for anyone that subscribes from now on.   They can still turn it on whenever they like and those that subscribed before 5:00pm or so (when I made this change) will have to turn it off themselves if they want the posting acknowledgements to stop.

Thanks again for everyone's help.   Feel free to to start up a few conversations tomorrow on the new list and continue to work the software.  I'll continue to monitor it.

Spencer