

Yes, its fine to have your OS on a separate SSD and use your HDD as data storage.
Its also important to maintain your drives. Be sure to have SMART alerts, and do spinrite or badblocks occasionally to let the drive firmware remove bad sectors from use.
Its perfect for a small VPS. Been using it for years.
I do occasionally get places where my email simply will not send to them, even though it follows every email standard properly and isnt blacklisted. For those rare occasions, ill use a third party email address to send, which then forwards everything to my main email.