could you please confirm if you receive any error at the time of sending email from Lightroom?
Which email client are you using?
Were you able to successfully validate your mail account in Lightroom?
Yes it said send email failed. I can validate it if I don't use a password. I have sent and received regular emails.
you need to validate the account using password.
You might want to check the email client details that you are entering while setting up the mail account in Lightroom.