First important concept is that you do NOT have to add any nameservers of Hostinger to Google Cloud or anywhere. The reason is that your web hosting is on Google Cloud and only nameservers of Google is required.
Therefore, you just ignore the message on Hostinger:
Your domain is not pointing to Hostinger
If you have pointed your domain to us, please keep in mind that domain propagation can take up to 24 hours to fully propagate. If you would like to point your domain to us, you will need to point your domain to our nameservers.
Second, access Email Delivery by choosing Email section of your domain. You will see a section Manage Email Delivery with three items: MX, SPF, DKIM with all inactive statuses.
The guideline of MX type is:
- Host: MX
- Points To: @
- Priority: mx1.hostinger.com and mx2.hostinger.com
- TTL: 14400
When you setup MX record set on Google Cloud, there are couple of things to be noticed. First the setup page is on Network Services > Cloud DNS. Then choose your zone name which has a set of NS records such as A, SOA, NS, etc.
- Add a new record set
- for DNS Name, you might type @ as following the guide of Hostinger but actually you just have to leave it blank!
- for resource record type, choose MX.
- for Preference and mall server, there are two parameters which are priority and the server name. Therefore, input 1 mx1.hostinger.com and add item to input another one which is 2 mx2.hostinger.com
- Save
- Click Verify DNS at the area of MX record on the page of Hostinger.
- If there is a tick with Active status, it’s successful.
If you type mail server without priority, there is a error prompted with invalid record. If you type @ for DNS Name, you are able to save but the status of MX record is never active.
The guideline of SPF type is:
- Type: TXT
- Host: @
- Value: v=spf1 include:_spf.mail.hostinger.com ~all
- TTL: 300
- Add a new record set
- for DNS Name, again, leave it blank!
- for resource record type, choose TXT
- for TXT data, input the value with quote sign: “v=spf1 include:_spf.mail.hostinger.com ~all“
- Save
- Click Verify DNS at the area of SPF record on the page of Hostinger.
- If there is a tick with Active status, it’s successful.
The guideline of DKIM type is:
- Type: CNAME
- Host: hostingermail-x._domainkey.foodragon.biz where x is a, b, c
- Points To: hostingermail-x.dkim.mail.hostinger.com where x is a, b, c
- TTL: 300
- Add a new record set
- for DNS Name, type hostingermail-a._domainkey
- for resource record type, choose CNAME
- for Canonical name, input hostingermail-a.dkim.mail.hostinger.com
- Save
- add another new record set
- similar with previous setting, just change a to b
- also, add one more new record set which is the group of c
- After that, you will have three CNAME records
- Click Verify DNS at the area of DKIM record on the page of Hostinger.
- If there is a tick with Active status, it’s successful.
Test the mail server by sending and replying emails. Cheers.
PS: You can also check the routes of your mail server on mxtoolbox.com. Some hostnames are listed if the mail server is connected.