BDS Mail (aka "Brain Dead Simple Mail") is an optional addition to the existing email server which comes installed as default. It creates an extra folder within the Mutt client which allows you to send and receive email using [[https://en.wikipedia.org/wiki/I2P][i2p]] as the transport layer. This solves the problem of being blocked by dubious systems and also the problem of user friendly email encryption. If you're behind a hostile firewall which you don't control and which blocks all ports, this system is still likely to work. You can use GPG as an additional encryption layer if you prefer, but it's not strictly necessary because you already have the i2p public key system to ensure end-to-end security.
It's unlikely that many people will use this. If it's hard to persuade anyone to use GPG or Enigmail then it will be /next to impossible/ to persuade them to switch to BDS Mail unless they're already obsessive about technical security. However, this provides yet another option for reasonably secure communications if other methods fail or are untrustable.
After installation exit from *Administrator controls* back to the user control panel then select the option to *show your email address*. You will now have a new bdsmail address which ends with /.b32.i2p/. If you then select *Use Email* to run the Mutt email client you'll notice that you now have a folder called *i2p*. If you select that folder (move up and down with /CTRL+n/ or /CTRL+p/ and open with /CTRL+o/) you can then send email from your new address, or receive mail to it. Just like ordinary email, but with a more random-looking address.