SMTPRecipientsRefused

[Flix6x]

I got a bug report for a broken password reset feature on one of our servers:

SMTPRecipientsRefused : [...] Sender address rejected: not owned by user [...]"

It turns out that some recipient mail servers will refuse emails for which the shown email address differs from the sender's real email address. So for example, using the following config settings will not work for those users:

MAIL_USERNAME = "no-reply@company.com"
MAIL_DEFAULT_SENDER = {
    "FlexMeasures",
    "no-reply@flexmeasures.company.com",
}

This is worth mentioning in the documentation, specifically, here.