If you want to allow all emails to be received from a specific sending email address - so that even mails classed as 'junk' will arrive - then you can 'whitelist' this address within Junk Mail Filters within the package.
- Login to Control Panel
- Locate the Junk Mail Filters icon
- Locate Allow by Sender and add a domain rule or a mailbox rule to allow mail to always be received from a specific address