Improve delivery rate of sent emails

[pascalfree]

There is a number of things that spam filters look for and that should adjust in our outgoing emails to not trigger them. Some might not be needed, but here is what I found could help.

• [x] Send from same domain: #191
• [ ] Tell user to set up SPF, DKIM and DMARC
• [ ] Always include the text part in HTML emails (I think we already do that) and make sure their contents match
• [ ] Members must tick a box when they register, that they agree to recieve the Emails. That does not affect the spam filter, but we should ask for permission
• [ ] Write "{Name} von {Organisation}" as the sender. This helps the reciever to correctly identify the email as non-spam
• [ ] Add physical address of the organisation in each email
• [ ] Make sure subject is not empty, does not consist of only capital letters and has at most one exclamation mark
• [ ] Add Opt-Out Link. #386 If opt out requires leaving the organisation, mention that and point to the place to do so.
• [ ] Option to exclude email from recieving emails because it does not exist, or has been rejected. If we keep sending there, we might raise red flags. Admins would in the meantime try to contact that member through other means to find their correct email address.
• [ ] Force the use of open URLs (link text matches href) or at least warn the sender.
• [ ] Inform users about tools to check if their IP is blacklisted or has a bad reputation: e.g. https://multirbl.valli.org/lookup/ and https://postmaster.google.com

Sources:

• https://sleeknote.com/blog/why-emails-go-to-spam
• https://mailchimp.com/resources/most-common-spam-filter-triggers/
• https://postmarkapp.com/blog/why-are-my-emails-going-to-spam

[motu55]

The important point fro me to keep in mind is to distinguish between documentation nescessary to install and run juntagrico and general devops stuff like how to configure my mail server, dns etc for the general devops stuff we might want to find a solution how to document it and pass it on to the members

[pascalfree]

One more point would be using individual emails with the TO field instead of one email with a big BCC.

This might help with the timeouts: https://pypi.org/project/django-mailer/

[patrickuhlmann]

We use Mailjet. It sends the emails reliably and the free plan allows sending of 6000 mails per month.