Add a simple mail queue in the database

Adds a function to call that will render a complete MIME message, and
write the resulting text to a database table.

Then there is a cron job that runs at regular intervals (every 5 mins or so)
and sends all the queued emails.

This brings in two important functions:
 * The ability to "send" emails from regular web views without the risk of ending
   up blocking on the SMTP server.
 * The abilitty to "transactionally send email" - meaning that mail sen this way
   will just disappear if the transaction (normally managed by django) that's open
   when it was sent ends up rolling back. This prevents re-sending email over and
   over again when some later step in the process fails.

1 files changed, 30 insertions, 0 deletions

diff --git a/postgresqleu/mailqueue/util.py b/postgresqleu/mailqueue/util.py
new file mode 100644
index 00000000..038a2058
--- /dev/null
+++ b/postgresqleu/mailqueue/util.py
@@ -0,0 +1,30 @@
+from email.mime.text import MIMEText
+from email.mime.multipart import MIMEMultipart
+from email.mime.nonmultipart import MIMENonMultipart
+from email.Utils import formatdate
+
+from models import QueuedMail
+
+def send_simple_mail(sender, receiver, subject, msgtxt, attachments=None):
+	# attachment format, each is a tuple of (name, mimetype,contents)
+	# content should already be base64 encoded
+	msg = MIMEMultipart()
+	msg['Subject'] = subject
+	msg['To'] = receiver
+	msg['From'] = sender
+	msg['Date'] = formatdate(localtime=True)
+
+	msg.attach(MIMEText(msgtxt, _charset='utf-8'))
+
+	if attachments:
+		for filename, contenttype, content in attachments:
+			main,sub = contenttype.split('/')
+			part = MIMENonMultipart(main,sub)
+			part.set_payload(content)
+			part.add_header('Content-Transfer-Encoding', 'base64')
+			part.add_header('Content-Disposition', 'attachment; filename="%s"' % filename)
+			msg.attach(part)
+
+
+	# Just write it to the queue, so it will be transactionally rolled back
+	QueuedMail(sender=sender, receiver=receiver, fullmsg=msg.as_string()).save()