This error is causing by bad credentials. Now, I've got another problem with the same configuration:

• Host -> Settings Host -> Base Settings -> Host Details -> E-mail Host : I put in this textbox the email address to sent reset password email. Email has this form: myaddress@mydomain.it
• Host -> Settings Host -> Advance Settings -> Settings SMTP Server
  
  • Server SMTP e porta: smpt.office365.com:587
  • Limit Connections: 1
  • Max Idle Time: 0
  • SMPT Authentication: BASE
  • SMTP SLL: checked
  • Username SMTP: myaddress@mydomain.it
  • Password: my password
• Admin -> Settings Site -> Advance Settings -> Settings SMTP Server -> SMTP Mode: Host

Now the error is: Mailbox unavailable. The server response was: 5.7.60 SMTP; Client does not have permissions to send as this sender

StackTrace:

   at System.Net.Mail.DataStopCommand.CheckResponse(SmtpStatusCode statusCode, String serverResponse)
   at System.Net.Mail.DataStopCommand.Send(SmtpConnection conn)
   at System.Net.ClosableStream.Close()
   at System.Net.Mail.SmtpClient.Send(MailMessage message)
   at DotNetNuke.Services.Mail.Mail.SendMailInternal(MailMessage mailMessage, String subject, String body, MailPriority priority, MailFormat bodyFormat, Encoding bodyEncoding, IEnumerable`1 attachments, String smtpServer, String smtpAuthentication, String smtpUsername, String smtpPassword, Boolean smtpEnableSSL)

progmr