first writedown of code

.gitignore

@@ -24,6 +24,7 @@ var/
 *.egg-info/
 .installed.cfg
 *.egg
+.venv/
 
 # PyInstaller
 #  Usually these files are written by a python script from a template

Pipfile

@@ -0,0 +1,11 @@
+[[source]]
+url = "https://pypi.org/simple"
+verify_ssl = true
+name = "pypi"
+
+[packages]
+
+[dev-packages]
+
+[requires]
+python_version = "3.7"

README.md

@@ -1,3 +1,33 @@
 # pysendmail
 
-Simple module for using sendmail from Python.
+Simple tool for sending email with sendmail, postfix or ssmtpd.
+
+Example:
+{{{
+    import pysema
+    
+    pysema.send(
+        ['alice@example.com', 'bob@example.com'],
+        'really good subject line',
+        'Message body goes here'
+        )
+}}}
+
+If you need to send some complex message, use [email.message][em] from the 
+Python standard library to construct the message (including header fields) and 
+pass it to the `send_message` function:
+
+{{{
+    import pysema
+    from email.message import EmailMessage
+    
+    msg = EmailMessage()
+    # compose message
+    
+    pysema.send_message(msg)
+}}}
+
+if something goes whoopsie a `pysema.SendMailException` is raised.
+
+
+[em]: https://docs.python.org/3/library/email.message.html

pysema.py

@@ -0,0 +1,63 @@
+''' simple tool for sending email with sendmail, postfix or ssmtpd
+
+    import pysema
+    send(
+        ['alice@example.com', 'bob@example.com'],
+        'really good subject line',
+        'Message body goes here'
+        )
+'''
+
+import subprocess
+from email.message import EmailMessage
+
+
+SENDMAIL_PATH = '/usr/bin/sendmail'
+
+
+class SendMailException(Exception):
+    ''' Exception while using pysema '''
+    pass
+
+
+def send(to=None, subject='', message='', **headers):
+    msg = create_message(to, subject, message, **headers)
+    send_message(msg)
+
+
+def create_message(to=None, subject='', message='', **headers):
+    if isinstance(to, str):
+        recipients = to
+    elif isinstance(to, (list, set, tuple)):
+        recipients = ', '.join(to)
+    else:
+        raise SendMailException('No recipients given')
+
+    # ensure that the 'from' keyword (if given) is uppercase
+    sender_mail = headers.pop('from', None)
+    if sender_mail is not None:
+        headers['From'] = sender_mail
+
+    headers['To'] = recipients
+    headers['Subject'] = subject
+
+    msg = EmailMessage()
+    msg.set_content(message)
+    for key, value in headers.items():
+        msg[key] = value
+
+    return msg
+
+
+def send_message(msg):
+    if not isinstance(msg, EmailMessage):
+        raise SendMailException('Type Error: not an EmailMessage')
+
+    try:
+        subprocess.run(
+            [SENDMAIL_PATH, '-t', '-oi'],
+            input=msg.as_bytes(),
+            check=True
+            )
+    except subprocess.CalledProcessError as e:
+        raise SendMailException from e