instead of a list, turn it into a list containing that string. This
avoids an apparently common newbie mistake -- passing in a single
string for the destination and have it treated as a sequence of
characters.
I did some bugfixes, and fixed a major problem with the esmtp suport (I
think the person who did that part misunderstood RFC1869) Some of the
interface fer esmtp-related things has changed as a result.
I also added some documentation to the SMTP class' docstring.