Spam filtering is usually done based on the IP address, you need to check if your IP address is on the IP Address Black List. If it is then your best option would be to destroy the droplet and create a new one.
On another note, are you using any security measures, a firewall? using HTTPS? etc , you need to protect your droplet from the hackers and the malicious activity that they can perfrom

I am also facing same issue .. My ip is not blacklisted but still the emails are going to spam folder

Please help.

Administering mail traffic can be a complicated subject these days. Have you deployed DKIM and SPF with your mail setup? Are you utilizing DMARC reporting? Are you receiving any error log entries from receiving mail servers that indicate they are delaying your traffic for SPAM reasons?

DKIM and SPF are good places to begin with helping maintain a good reputation on the internet. DKIM and SPF are anti spoofing specifications that help receiving mail servers know mail traffic is legitimate. DMARC allows you to receive reports on your policies from major ISP providers around the world.