Normally, the email hosting server will be identified by the MX Record. MX records point a domain’s incoming email to the email provider responsible for processing those messages. In order to find the MX records, it’s necessary to perform an MX lookup. Here are some techniques:

1) Using free online services such as MXToolbox, Misk, Whois will give you a list of MX records that usually offer a provider’s name and corresponding IP addresses records

2) Using NSLOOKUP to view Mail Exchange (MX) records (NOTE: Only applies to Windows system) 

2.1: Open a command prompt

2.2: Type “nslookup” then press Enter

2.3: Type “set type=mx” then press Enter

2.4: Type the domain name that you want to look up, then press Enter

Boom! Now you got the MX records of that domain