https://github.com/metamarcdw/PyBitmessage-I2P
This is a fork of PyBitmessage that runs natively over I2P (ONLY) It requires a running I2P router with SAM Bridge activated.
You must also have the i2p SAM python module installed:
git clone https://github.com/i2p/i2p.i2p.git
cd i2p.i2p/apps/sam/python
python setup.py install
You must also insert a new config entry into your keys.dat file to enable bootstrapping from the eepsite:
bootstrapeepsite = pybitmessage-i2p.i2p
Just to be clear, so far it has only been tested from source.
UPDATE: A Windows binary has been created using PyInstaller. It has been tested and is working under Windows 8.1. It is available from the GitHub repository as PyBitmessage-I2P.exe
PyBitmessage-I2P has several important differences from vanilla Bitmessage. Always remember THIS IS A SEPARATE NETWORK! PyBitmessage-I2P forms a completely new and separate Bitmessage network inside of I2P. Since this is a new network, the client must bootstrap by accessing an eepsite and reading a list of known nodes. This bootstrapping process can cause delays if your I2P router is not well integrated with the I2P network. Another important difference to take note of is that the format for Bitmessage addresses has been changed slightly to signify that you are seeing a BM-I2P address rather than a vanilla address. PyBitmessage-I2P addresses start with "BM+" rather than "BM-".
If you would like to contribute to the network by running a node 24/7 for newcomers to bootstrap from, navigate to your Network Settings dialog and send a copy of your I2P destination string to:
BM+2cToiiYrW92SSZ3616VTgQYmSmg5bVDi8w (PyBItmessage-I2P)
BM-2cToiiYrW92SSZ3616VTgQYmSmg5bVDi8w (Vanilla Bitmessage)