### Install Purepythonmilter from sources

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/src/purepythonmilter/examples/README.md

Clones the repository, navigates into the directory, and installs the package with example dependencies.

```console
$ git clone https://github.com/gertvdijk/purepythonmilter.git
$ cd purepythonmilter

# N.B. You may want to create and activate a Python virtualenv at this point.

# This installs the package at the current location (`.`) with the `examples` option
# to indicate extra dependencies to be installed.
$ python -m pip install -e .[examples]
```

--------------------------------

### Run an example Milter app

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/src/purepythonmilter/examples/README.md

Starts the debug_log_all example Milter application, binding it to a specific host and setting the log level.

```console
$ python -m purepythonmilter.examples.debug_log_all \
    --bind-host 172.17.0.1 \
    --log-level=INFO
```

--------------------------------

### Installing project with development and example dependencies

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/CONTRIBUTING.md

Command to install the project in editable mode with extra dependencies for development and examples.

```console
$ pip install -e .[development,examples]
```

--------------------------------

### Build and run Postfix instance in Docker

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/src/purepythonmilter/examples/README.md

Uses a Makefile to build and start a Postfix container.

```console
$ make -C postfixtest
```

--------------------------------

### Install Purepythonmilter

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/README.md

Install Purepythonmilter using pip.

```console
pip install purepythonmilter
```

--------------------------------

### PurePythonMilter Class Construction Example

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/api.md

An example demonstrating how to instantiate the PurePythonMilter class with specified hooks and flags.

```python
mymilter = PurePythonMilter(
    hook_on_connect=my_on_connect,
    can_add_headers=True,
)
```

--------------------------------

### Self-descriptive example Milter app

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/README.md

A self-descriptive example Milter application demonstrating basic functionality.

```python
import purepythonmilter as ppm


async def on_mail_from(cmd: ppm.MailFrom) -> ppm.VerdictOrContinue:
    if cmd.address.lower().endswith("@example.com"):
        return ppm.RejectWithCode(primary_code=(5, 7, 1), text="not allowed here!")
    return ppm.Continue()


mymilter = ppm.PurePythonMilter(name="mymilter", hook_on_mail_from=on_mail_from)
mymilter.run_server(host="127.0.0.1", port=9000)
```

--------------------------------

### Connect to Postfix using telnet

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/src/purepythonmilter/examples/README.md

Initiates a telnet connection to the Postfix instance on port 25.

```console
$ telnet "$(make --silent -C postfixtest get-ipv4)" 25
```

--------------------------------

### Get Postfix container IPv4 address

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/src/purepythonmilter/examples/README.md

Retrieves the IPv4 address of the running Postfix Docker container.

```console
$ make --silent -C postfixtest get-ipv4
```

--------------------------------

### Send email using SWAKS

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/src/purepythonmilter/examples/README.md

A one-liner command to send an email using SWAKS to the Postfix instance.

```console
$ swaks --to user@test.local --server $(make --silent -C postfixtest get-ipv4)
```

--------------------------------

### Macro Definition Example

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/milter-protocol.md

An example of how DEFINE_MACRO commands with multiple symbols are encoded, including NULL termination and separation, and how symbols longer than a single character are wrapped in braces.

```text
C{mysymbol}NULLmyvalueNULL{othersymbol}NULLothervalueNULLiNULLABCD1234NULL
```

--------------------------------

### SMTP Server Greeting Example

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/smtp-recap.md

An example of the initial greeting message from an SMTP server.

```text
220 myhost.g3rt.nl ESMTP Postfix (Debian/GNU)
```

--------------------------------

### Running the all-linters script

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/CONTRIBUTING.md

Command to execute the run-all-linters script and shows an example of successful output.

```console
$ ./run-all-linters
[...]
Everything looks OK! 🎉
```

--------------------------------

### Running pytest to verify tests

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/CONTRIBUTING.md

Command to execute all tests using pytest and shows an example of successful output.

```console
$ pytest
[...]
==== 211 passed in 1.09s ====
```

--------------------------------

### Example of well-crafted commits

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/CONTRIBUTING.md

Illustrates a structured approach to commit history for a pull request.

```git
HEAD   Implement feature X
-- the aim of the pull request

HEAD^  Refactor module Y to allow for subclassing ClassZ
-- improvement, but preparatory change

HEAD^^ Add tests for current logic in module Y
-- not a functional change in itself, but purely preparatory to assert a before-change
state is tested for.
```

--------------------------------

### Options Negotiate Symbols List Encoding

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/milter-protocol.md

Example encoding for the Options negotiate response, including macro stage ID and a space-separated list of symbols, NULL-terminated.

```text
\x00\x00\x00\x01j {my}\x00\x00\x00\x00\x00\x03k {other}\x00\x00
```

--------------------------------

### Setting up the development environment with direnv

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/CONTRIBUTING.md

Commands to link the .envrc-example and allow direnv to manage the virtual environment.

```console
$ ln -s .envrc-example .envrc
$ direnv allow
```

--------------------------------

### Applying the Apache License

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/LICENSES/Apache-2.0.txt

This snippet shows how to apply the Apache License to your work by including a boilerplate notice.

```text
Copyright [yyyy] [name of copyright owner]

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
```

--------------------------------

### Upgrading base Python packages

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/CONTRIBUTING.md

Command to ensure pip, setuptools, and setuptools-scm are up-to-date within the virtual environment.

```console
$ pip install --upgrade pip setuptools setuptools-scm[toml]
```

--------------------------------

### Create an annotated and signed git tag

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/releasing.md

Steps to create a signed git tag for a release.

```console
$ git status  # Should show 'nothing to commit, working tree clean'
$ git branch --all --contains HEAD
$ git tag --annotate --sign --message="<Release description>" <tagname>
```

--------------------------------

### Build source distribution and wheel

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/releasing.md

Build a Python source distribution file and a wheel using the 'build' tool.

```console
$ rm -rf dist/
$ python -m build
$ ls -l dist/
```

--------------------------------

### Upload to PyPI testing and verify

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/releasing.md

Upload packages to the test PyPI repository and verify the release.

```console
$ twine check --strict dist/*
$ TWINE_USERNAME=__token__ twine upload --sign --repository testpypi dist/*
```

--------------------------------

### Check wheel contents

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/releasing.md

Run the 'check-wheel-contents' linter on the built wheel.

```console
$ check-wheel-contents dist/purepythonmilter-*.whl
```

--------------------------------

### Upload to regular PyPI

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/releasing.md

Upload the release packages to the regular PyPI repository.

```console
$ TWINE_USERNAME=__token__ twine upload --sign dist/*
```

--------------------------------

### Checking for outdated packages

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/CONTRIBUTING.md

Command to list any outdated packages in the current virtual environment.

```console
$ pip list --outdated
```

--------------------------------

### Push git tag to GitHub

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/releasing.md

Push the created git tag to the GitHub repository.

```console
$ git push <remotename> refs/tags/<tagname>:refs/tags/<tagname>
```

--------------------------------

### Generate SHA256SUMS file

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/releasing.md

Generate a SHA256SUMS file for the distribution files and verify it.

```console
$ (cd dist/ \
   && sha256sum purepythonmilter-*.{tar.gz,whl} > SHA256SUMS \
   && sha256sum --check SHA256SUMS)
```

--------------------------------

### SMFIC_QUIT_NC Command Definition

Source: https://github.com/gertvdijk/purepythonmilter/blob/develop/docs/milter-protocol.md

Defines the SMFIC_QUIT_NC command in Sendmail's libmilter, which suggests reusing the connection.

```c
#define SMFIC_QUIT_NC		'K'	/* QUIT but new connection follows *

```

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