IP address for Email server
To be able to send emails, your IP address reputation is capital. Make sure you go through the following point before sending Emails.
The first rule is to get a static IP. Most receiver will simply reject email from dynamic IP. Whether you like it or not, you have no choice but to follow this rule.
Antispam software heavily use IP blacklists to detect fraudulent messages. You must ensure that the IP address you send from is not in one of those blacklists.
There are several free tools to check if your IP address is blacklisted. I personally use
Both offer free periodic checks of your addresses.
The whitelist is the opposite of the blacklist. Make sure you remove your address from blacklists before adding it to a whitelist.
In a very Microsofty way, Outlook.com (and Hotmail, live) have their own rules. It is also quite hard to find your path through the documentation. Thankfully, they provide useful tools once you manage to find them.
The first one is Smart Network Data Service. It allows you to check if you IP addresses are blacklisted. You first need to add and confirm your IP addresses. Once all your IPs are present in Access Control, you can go in View IP Status to check if you have some blocked IP addresses.
In case you have some blocked address, you can request unblocking there https://support.live.com/eform.aspx?productKey=edfsmsbl3&ct=eformts&scrx=1