OG Mailinglist and Mailgun

General setup

OG Mailinglist works well with Mailgun backend. Just make sure you set correct API key, username and password on admin/config/group/mailinglist configuration page.

Reducing Mailgun load

Mailgun counts both incoming and outgoing emails. To reduce this, one could send email from the server and only use Mailgun for the incoming emails, which for largers mailinglists is just a fraction of all outgoing emails (someone please clarify if Mailgun counts email going to group as single email or counts all the recipients as well).

To use this feature go to the admin/config/group/mailinglist page and check "Do not use Mailgun for outgoing email". In case servers start rejecting your mails, make sure that you are not relaying any spam (especially hard on shared hosting), add an MX record to DNS with your server IP, or follow instructions which get returned if your mail gets rejected.