I'm interested in creating a new webmail platform based on Python and Django, which will be free software & open source - Speedy Mail 2.0 (Speedy Mail 1.0 and 1.1 were based on a Perl software - Endymion MailMan web-mail, from 2000 to 2005). I want Speedy Mail 2.0's features to be as similar as possible to Gmail - with labels (a message can have several labels, or none), filters (to apply labels automatically, skip the inbox, mark as read etc.), 12 different stars, composing more than one mail at a time, etc. I would like to know if there is any free software in Python and Django we can base Speedy Mail on, or maybe something in another language (such as PHP) which we can convert to Python and Django? And are you interested in helping me develop Speedy Mail, or do you know where I can find developers who may be interested?
By the way, is there a simple way to convert PHP software to Python, or do we have to rewrite it again line by line? I found some free software packages for webmail, some of them are in Python (Mailpile, Modoboa) and some in PHP (Roundcube, AfterLogic), and there are others not listed here.
Which protocols we should use to connect to the mail server? I understand that IMAP has folders but not labels/tags, does it mean we can't use it? Is it better to use POP3?
Which license do you recommend using? I'm thinking about using the GNU Affero General Public License (Affero GPL), you can read about it on the GNU website - it's like the GPL but also requires to publish the source code if you use it on a server. I think I prefer this license to ensure that if people or companies use my software, they will publish their source code (of course this will have to be enforced).