Add extra troubleshooting, readability changes

README.md

@@ -7,7 +7,7 @@ same setup time and time again.
 I've linked this file on Github to a shorter, more memorable address on my
 website so you can get it on your machine with this short command:
 
-```
+```sh
 curl -LO lukesmith.xyz/emailwiz.sh
 ```
 
@@ -22,7 +22,7 @@ actually works perfectly.
 
 - **Postfix** to send and receive mail.
 - **Dovecot** to get mail to your email client (mutt, Thunderbird, etc).
-- Config files that unique the two above securely with native log-ins.
+- Config files that link the two above securely with native log-ins.
 - **Spamassassin** to prevent spam and allow you to make custom filters.
 - **OpenDKIM** to validate you so you can send to Gmail and other big sites.
 
@@ -104,7 +104,7 @@ email program. For my domain, the server information will be as follows:
 - SMTP port: 587
 - IMAP server: `mail.lukesmith.xyz`
 - IMAP port: 993
-- Username `luke` (I.e. *not* `luke@lukesmith.xyz`)
+- Username `luke` (i.e. *not* `luke@lukesmith.xyz`)
 
 The last point is important. Many email systems use a full email address on
 login. Since we just simply use local PAM logins, only the user's name is used
@@ -115,8 +115,6 @@ login. Since we just simply use local PAM logins, only the user's name is used
 
 You're a big boy now if you have your own mail server!
 
-You can tweak Postfix (sending mail
-
 ## Benefited from this?
 
 If this script or documentation has saved you some frustration, you can donate
@@ -135,3 +133,5 @@ to support me at [lukesmith.xyz/donate](https://lukesmith.xyz/donate.html).
   worry if you are: sometimes especially new domains are automatically assumed
   to be spam temporaily. If you are blacklisted by one of these, look into it
   and it will explain why and how to remove yourself.
+- Check your DNS settings using [this site](https://intodns.com/), it'll report any issues with your MX records
+- Ensure that port 25 is open on your server. [Vultr](https://www.vultr.com/docs/what-ports-are-blocked) for instance blocks this by default, you need to open a support ticket with them to open it. You can't send mail if 25 is blocked