You need to be sure about port 25 block on the server hosting site. You can always contact them and ask for the same.
Remember, the port block is assigned to server ip and not on account level. It all depends on the hosting provider how this is done. In Amazon AWS, Google Cloud, Oracle Cloud, its all per IP based block. For each server ip, we need to contact support to unblock it.
For Upcloud hosting provider, its account level block and if the block is lifted then all server ips are unblocked.
Dont have knowledge about how Vultr does this. But I believe its per IP level and you will need to contact them to unblock on each IP