Mailman 3 Best Practices

Unfortunately, due to years of increasingly high volumes of spam messages the Internet has become much more hostile to email senders than it was in decades past. However, while 100% delivery success cannot be guaranteed it is possible to enjoy consistently high rates of successful delivery by following best practices for mailing list operators.

1) Email sender basics - reverse DNS, SPF, DKIM, and DMARC records in your DNS. Reverse DNS is something your hosting provider handles, but the others will need to be setup through whomever manages your domain's DNS. SPF identifies specific servers authorized to send mail for your domain, DKIM electronically signs the message headers to verify authenticity, and DMARC tells receiving mail servers both that you have these authentication processes in place and how handle unauthenticated mail. Collectively, these help receiving mail servers identify legitimate mail from your domain and demonstrate your good faith as a legitimate mail sender - and by doing so, you improve your chances of successful delivery with all major mail providers.

2) Ensure your list members are legitimate subscribers - require opt-in with confirmation to prevent fake sign-ups, and don't use email lists supplied by a third party. This makes it less likely message recipients will complain to their mail provider or mark your messages as spam, and will minimize potential harm to your reputation as a sender resulting from such complaints.

3) Respect bounces and unsubscribe requests. Sometimes bounces are a result of temporary delivery issues to a particular provider, but they are also caused by mail accounts that are full, have been deleted, or were misspelled in your subscriber list. Similarly, unsubscribe requests are sometimes due to a series of bounces but can also be because a subscriber is no longer interested in receiving list messages. Legitimate mail senders and mailing applications are expected to respond to repeated bounces or unsubscribe requests by no longer sending messages to that address, and continuing to send messages anyway can (and likely will) harm your sending reputation with that provider.

Specifics of these best practices are covered in further detail in other knowledgebase articles. You can also ask your hosting provider for further detail if needed.