Likelihood of Mail Server Changing

I’m considering using my dreamhost account to manage all my incoming email, and I’d like to know the likelihood that my MX servers will change hostnames (IPs are fine).

I already have my own servers in a colo (not at dreamhost), and those run mail, dns, and web. The issue is my email server isn’t great at handling sudden spam floods and such, and I’m sure dreamhost is much better at handling this.

So what I’ve been doing is configuring my DNS (which resides on my servers, not at dreamhost) so that the MX records for my domain point to dreamhost. In dreamhost, I have set up a domain there with just mail services and DNS (I couldn’t find a way to turn off DNS). Dreamhost says my MX servers for the domain are mx[1-3]

I then configure my dreamhost mail to forward email for listed senders to the mail servers in my colo. This means that I can let dreamhost’s mail servers handle the barrage of incoming spam and throttle/filter accordingly. I could configure this on my own mail server, but I don’t trust my expertise in this area.

So back to my question. What is the likelihood that my mail servers will change from mx[1-3] to something else? I know the IPs may change but that’s not a problem since my MX records point to the hostname, not IP.

Since I’m doing my own DNS on my own servers, I won’t know if the MX records change unless I query dreamhost’s DNS for my domain (which is not authoritative – I point DNS in my whois record to my own DNS servers).

I know one solution is to let DH handle DNS, but I want to keep control of that since it’s so vital. I can survive a short-term email outage since it’s not vital to my business, but DNS or web outages I have less tolerance for. I’d rather keep these items in my control.

Any thoughts much appreciated.