Mailer-Daemon Scam

I recently received a spam email via text email is mailerdaemon@mmscmail.meteor.ie

I did not know you could just email send it as a scam

which looked somewhat like an email and has an attachment which does not open thankfully. The message said it was from mailerdaemon@mmscmail.meteor.ie as I said up top in messages (I'll attach screenshots of the text below). The problem is I haven't sent any emails recently and it looks almost as if an email was sent from my phone number. What is going on?? I have never sent emails from my phone number and I don't understand what this text means and the attachment .