SMTP Authentication is disabled in SmarterMail after domain creation in Plesk: option "Require SMTP Authentication" is unchecked in SM > Domains > example.com > Technical
Bug registered with ID #PPPM-6389.
As a workaround, settings should be set for each domain in SmarterMail manually.
Custom fix for Plesk Onyx 17.5:
- Unpack the archive from the attachment;
- Place the files in