EMAIL_BACKEND = 'django.core.mail.backends.smtp.EmailBackend'

# Host for sending e-mail.
EMAIL_HOST = 'mytdl.de'

# Port for sending e-mail.
EMAIL_PORT = 25

# Optional SMTP authentication information for EMAIL_HOST.
EMAIL_HOST_USER = 'me@mytdl.de'
EMAIL_HOST_PASSWORD = config('EMAIL_HOST_PASSWORD')

(535, b'5.7.8 Error: authentication failed: authentication failure')

telnet  mytdl.de 25

2.7.0 Authentication successful

AUTH CRAM-MD5

AUTH LOGIN