LINUX - How to lookup SMTP settings for exchange server

How to lookup SMTP settings for exchange or anything
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From inside your Domain. Lets say im inside the domain "server.com"

(step1)
FROM WINDOWS:
Open cmd

nslookup
> server <DNS SERVER>  # Use your internal DNS
> set q=MS
> server.com

you will see the mail servers, for example lets say you get:
smtp.server.com
mail.server.com

OR FROM LINUX:

dig netgear.com ANY +noall +answer

(step2)
FROM LINUX:
NOTE: Dont have to use NMAP There are websites that can scan ports for you 2:

Now we need to nmap to see the open ports
nmap -A -v mail.server.com

We will see lots of open ports as its a mail server
Discovered open port 25/tcp on 209.249.181.6
Discovered open port 443/tcp on 209.249.181.6
Discovered open port 587/tcp on 209.249.181.6
Discovered open port 993/tcp on 209.249.181.6
Discovered open port 110/tcp on 209.249.181.6
Discovered open port 80/tcp on 209.249.181.6
Discovered open port 995/tcp on 209.249.181.6

We know that 587 is a common mail port and its secure, so we enable TLS

Our conclusion:
Server: mail.server.com
Port: 587
TLS: on

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