SMTP 5.1.1 Error when sending an email, What does it mean?
SMTP 5.1.1 Error message indicates the email account doesn't exist at the organisation or domain the message was sent to.
Prolateral Consulting Ltd
Bramingham Business Centre, Enterprise Way, Luton, Bedfordshire, LU3
VAT No. GB 814 3886 16 | Company Reg No. 4676923