I am using a WP droplet and trying to configure my GMAIL SMTP account on it (I was intending to use the WP-Mail-SMTP plugin, but somehow this is not working (my browser freezes even when I am trying to send the e-mail test from the plugin platform).
It might be because your DigitalOcean account is fairly new, which means that sometimes there's a filter activated to block SMTP to avoid spam on the platform.
You need to contact Support via the control panel to get unblocked.
Another solution I would recommend that you have a look at SparkPost as an alternative way of sending mails via WordPress.
https://www.sparkpost.com
https://wordpress.org/plugins/sparkpost/
Thank you very much for the real quick reply. I've managed to contact support guys (which also replied really quickly) and the problem is now solved =)
check your server port allowed
make sure port tls and ssl is allowed.
install ufw thank check status ufw
good luck