550 5.1 1 user unknown unknown recipient July 8, 2019 16 32 64 128 550 5.1 1 user unknown 550 5.1 1 unknown recipient in reply to rcpt to command Reply 550 5.1 1 user unknown unknown recipient Recipient address rejected user unknown in virtual mailbox table 550 5.1.1 unknown user Sender address rejected not owned by user
