Mail relay, for example from postfix, where to start raising, what to read?

Question

Email

The company has corporate mail on office365, mailboxes are already configured.
We set the task to raise the mailer (any one, I have chosen postfix so far, but maybe zimbra or zentual is easier). When sending a letter from an email client, the letter must go to the local postfix, and be sent via office365 to the recipient.
Let's say Vasya Pupkin sends a letter, it goes to the local postfix, and then goes to the recipient through Vasya Pupkin's account on the office365 server.
Since I didn’t work with mail servers, it’s hard to even start googling, I managed to get the local root user to send a letter through the gmail account. And here you need the mail client to register on our server, and depending on its name, the letter was sent through its account to office365.
Tell me what to read, and is it possible to do this quickly according to the articles? Or is it better to read a postfix book?

Answer 1

I'll add to the words of Peter Ivanov that relay can also be made from postfix or exim - Google knows how. You only need user authorization to send.
And here's how to enable relaying on Office365: https://technet.microsoft.com/en-us/library/dn5543...