The environment variable for PDS email settings are these two:
PDS_EMAIL_SMTP_URL=smtps://username%40mail.example.com:(a password without special characters)@smtp.eu.mailgun.org:465/
PDS_EMAIL_FROM_ADDRESS=username@mail.example.com
Tips
URL-encode username and password
Usernames for SMTP sending often have the email address as the username. Everything in the smtp URI in the env file needs to be url-encoded.
So, if your username is “username@maildomain”, then it needs to be entered as “username%40maildomain” in the
TO CONFIRM: password also needs to be URL encoded (or, just make sure it doesn’t have any special characters)
Services
Mailgun
The general syntax for SMTP for Mailgun is “username@maildomain”, password, @ smtp.mailgun.org or smtp.eu.mailgun.org
Forward Email
Users are “username@maildomain”, you will need to enable a password for the alias you are using (and use the same “from” name). It also can take up to 24 hours for a new domain to get enabled for email sending.
Use a wildcard alias and enable a password for it to send SMTP if you’d like different from address, e.g. “*@maildomain”. In the URI, the asterisk * needs to be url encoded as %2A, and the @ sign needs to be urlencoded as %40 as per usua, so this would look like “%2A%40maildomain”