I took the liberty to check your DNS records - https://who.is/dns/hostinko.com
It looks like your SPF and DKIM records are not setup properly.
To get your email directly to Inbox, Please set your DKIM and SPF records properly and keep sending good emails, believe yours will be transactional emails only, since it is a Hosting company, As long as someone else hosted on the same IP is not sending any spam emails, You email should start landing directly to Inbox within next 24 hours.
Also here is a great tool, to send a Test email- www(.)mail-tester(.)com (Since I can post only one link)
Since you are using WHMCS, you can simply create a Support ticket to the given email and check your sender score, and then improve it according to the above instructions.
Let me know if you need any other help.