New users unable to login

Hi All
I managed to get kobotoolbox working last year.

Now i have an issue where new users cannot login (existing users can login)

New users just get “Please enter a correct username and password. Note that both fields may be case-sensitive”

Also after registering new users are getting server error 500 - Any the activation emails are not being sent out.

Password reset link is not being sent out.

Steps taken

  1. SMTP account details / password is still working ( i can login to the mailbox)
  2. redeployed kobotoolbox
  3. rebooted the server
  4. Set firewall rule to any any
  5. activated the user under admin url https://kobo_domain/admin
  6. telnet to smtp address connects.
    7)mailbox in question is not full.

any other troubleshooting steps would be much appreciated

ok it turned out to be conidiation access policy blocking the mail account from logging on.

Thank you for sharing the solution with the entire community. It should be helpful for those having similar issue.