Sparkpost should look something like this:
DISCOURSE_SMTP_ADDRESS: smtp.sparkpostmail.com # (mandatory)
DISCOURSE_SMTP_PORT: 587 # (optional)
DISCOURSE_SMTP_USER_NAME: SMTP_Injection # (optional)
DISCOURSE_SMTP_PASSWORD: 789c9e1234ce4e3f501347a8f0b7a087e9f62bb1 # (optional, WARNING the char '#' in pw can cause problems!)
DISCOURSE_SMTP_ENABLE_START_TLS: true # (optional, default true)
I don’t know whether sparkpost has port 2525 open. TLS & Port 587 is safer/better anyway.
Everything (except the password) should be exactly like that.
./launcher rebuild app and you should be good to go.
The one other tricky thing is that if your Discourse domain is something.yourdomain.com and you’re trying to send mail with email@example.com, you need to pay attention to this section:
## If you want to set the 'From' email address for your first registration, uncomment and change:
- exec: rails r "SiteSetting.firstname.lastname@example.org'"
## After getting the first signup email, re-comment the line. It only needs to run once.