For each mailing list you want to manage you have to create a working directory and put inside a file named `config.yml` with your SMTP server and letter configuration.
Note that if already you use [MuList](https://github.com/kimihub/mulist) to manage your mailing list, the existing working directory can be the same for MuLetter. In that case, you just have to to fill your existing `config.yml` file.
Example of `config.yml`:
smtp_user: username
smtp_password: password
smtp_host: smtp.hostname.com
smtp_ssl: true
letter_from: letter title <username@hostname.com>
letter_subject: subject letter
Once `config.yml` is created you should be able to use the `muletter` command in your working directory.
## SMTP Limitations
Using a SMTP server with a standard configuration and your own domain is strongly advised to make sure that your letter will not be seen as a junk mail by free mailbox services like Gmail, Yahoo or Outlook.
Plus, SMTP of these free services are too limited to send such a number of mails in the same day.
You'll also have limitations with the SMTP of your registrar or web hosting but it should be enough for a letter with a small frequency and a small mailing list (in most of case, **lower than 500 mails per day**).
## Mailing List, Body, Attachments
The mailing list, body and attachments must be in the working directory named `list.txt`, `body.txt` (or `body.html`) and `attachments/*.*`.
For the body you can use html syntax with mail limitations. You have to put all attachments in the sub-directory `attachments`.
