During email delivery, how do MTA, MDA, POP/IMAP connect with each other?

I have already read [Why use Dovecot AND Postfix/Sendmail?](https://serverfault.com/questions/626803/why-use-dovecot-and-postfix-sendmail) , [Why use both Dovecot and Postfix?](https://serverfault.com/questions/716653/why-use-both-dovecot-and-postfix) , [Why use both Dovecot and Postfix?](https://superuser.com/questions/962074/why-use-both-dovecot-and-postfix) which give the general idea, but here I'm looking for more precise details to understand how email servers connect together. Let's say I own the domain example.com with DNS configured like this: example.com MX mail.example.com mail.example.com A 1.2.3.4 and postfix and dovecot are intalled on my Debian server of IP 1.2.3.4. Let's say I send an email: * from my ISP address johndoe@myisp.com, from my local computer Thunderbird * ... to the address johndoe@example.com **What is the big picture of the different connections that will happen during this process?** Is the following correct: 1. My local computer connects to smtp.myisp.com (port 25 or 587) 2. My ISP's SMTP server (postfix?) queries the DNS of example.com and eventually will connect to mail.example.com, i.e. my own server where postfix is listening on port 25 or 587 3. My server's postfix saves the email on disk (where, by default?) 4. or postfix sends the email to dovecot (how do they connect together?) 5. When eventually I want to fetch mail on johndoe@example.com with another Thunderbird account, the computer will connect my server 1.2.3.4 on port 110 or 995 (POP3). ? In this case, postfix is the MTA, dovecot is the POP3/IMAP server, but what is the MDA/LDA (Delivery Agent)?