email – How do I communicate with a mail server I just set up?

I’m a total novice when it comes to web and am trying to wrap my head around emailing. I’m currently messing with this tutorial on setting up a mail server. I’ve been working my head around a lot of stuff about authentication and security, and I have a vague, perhaps functional understanding of what’s going on in this tutorial, except for two things which I will list here.

Firstly, at the end of the tutorial..

Congratulations. You have successfully configured your mail server and
you may test your account using an email client:

  • Username:
  • Password: email1’s password
  • IMAP:
  • SMTP: Note: use port 993 for secure IMAP and port 587 or 25 for SMTP.

Does this mean that if I send an email using my personal email account on, say YahooMail or something, my dummy email account I created will be able to communicate with my personal email account’s mail transfer agent (obeying rules given by SMTP or IMAP), which is then downloaded by a server that does stuff that obeys POP3 (hopefully this likely abuse of language is understood) to then put the email in the dummy email’s inbox?

What exactly has been achieved here?