A directory for client sessions will be created in the directory your config file is in. However, the files in there are rotated so you always have access to the previous 9 versions of the file.
Just invite the bot accounts to the rooms they should post in, and enter the room IDs of those rooms in the config file. They will join when the first email arrives.
**Hint:** Encryption works flawlessly when the bot account has logged in once before, there can be minor issues otherwise. You can just do a dry run of matrixmailer with the clients already specified in the configuration file to do that.
Feel free to join #matrixmailer:a-0.me to ask questions and discuss, or even to just leave feedback!
You can build the code using cargo, as usual. Make sure to install `openssl`, `openssl-devel` and `cmake` packages (naming may be different on your Linux distro), they are required to build the matrix-rust-sdk.