The linode secondary DNS feature is really great. Some people running their own server use it for e-mail and it would be wonderful if Linode provided a secondary MX service (like rollernet.us, although this wouldn't need that level of sophistication). Mail servers are, like DNS, low-cpu-load, have low memory requirements, and are easy to administer. This would allow customers to use Linode as a one-stop-shop for all their "make sure that things still get to me eventually if my servers are down" needs.

Backup MXs attract a HUGE amount of spam, because spammers believe (often correctly) that the anti-spam setup on a backup MX is likely to be missing or out-of-date. This would be true for the kind of store-and-forward service you're proposing.

If you really need a backup MX, then get another Linode in a different data center, or convince a friend to trade backup MX services. Anyway, how often are you down for 4 days?

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The irony is that Bill Gates claims to be making a stable operating system and Linus Torvalds claims to be trying to take over the world.
-- seen on the net

First of all, you DON'T have to be down for four days to cause email to bounce. Being down for a few hours will do it. Maybe the RFCs say clients are supposed to retry for that period, but real-world experience says that's not how it works.

I already do have three backup MX servers. E-mail is important.

About spam: a decent Amavisd-new installation takes care of most of it. You use DNSBLs, a valid-recipients list, and you keep a Spamassassin install which will detect things like forged MUAs (almost always spam). As I mentioned in my post, rollernet.us does this on a grand scale and they handle the spam gracefully. Take a look at them. They're really good.

I just think that having service like this would be a selling point for Linode. The way they market the service seems targeted at people who are trying to learn how to run their own internet services (maybe because business customers looking for a VPS don't need to be advertised at on a web site, they'll just look at the featureset and SLA). If you can say "have no fear in setting up your own vanity email address - we'll hold your mail for you if you make a mistake!" it'd be reassuring to those individuals.

Then these sources already lose emails (greylisting, temporary network / DNS errors, overloaded servers, Yahoo servers limiting delivery rate, ...), they should not be surprised if they lose some more.



If you have the time...



And handle all the diverging requests for different antiSPAM features ? I'd be surprised they'd want to open this can of worms.



That would be misleading at best... Configuration mistakes can make a mail server throw mails away too... If someone isn't comfortable administering an email server he/she would be better off using a free email provider.

I agree it would be nifty, and I agree backup MX is an important part of properly operating a domain, but the resources required to do this for a large number of domains are absolutely phenomenal.

Unlike the DNS service, which Linode can provide with a pretty reasonable investment of hardware and admin time, I think there's a pretty good chance it wouldn't be economical to provide backup MX for free. If it were one of the paid extras, maybe.

The problem with a "generic" backup-MX service is that peoples needs are different; eg I might not want antivirus filtering because I'm performing a research project on how many viruses hit my mailbox (I'm not, but I _could_ be); similarly I might want to feed all the spam into baysian filter. Whereas Fred wants to block everything possible.

The customisation requirements become horrendous. It's not practical.

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Rgds
Stephen
(Linux user since kernel version 0.11)

There are plenty of services that offer Backup MX, so it is practical. Some are more customizable than others. If you don't like how it is configured you don't have to use it. I'd bet most people won't need any advanced features like virus scan, spam filter, etc. since they are already doing that on their primary server anyway.

Okay, but there's other stuff. Eg, what's the server's SPF policy?

It's too late. I don't have the remote IP, so I can't greylist or DNSBL, both of which (in my experience) are major spam rejectors. I can't bounce, because bouncing spam/viruses is a *bad* idea. All I can do is drop it on the floor, which means false positives won't be seen by the sender.

I came to Linode because it lets me have my own (virtual) server, which I control, and on which I can do anything that doesn't piss off my neighbors, for a lot less than an actual machine. I think they should concentrate on providing the best virtual servers they can, and let others provide other services.

Another thought: Having Linode provide backup MX isn't going to help when Linode goes under. Better to have it somewhere else, holding your mail while you scramble to get a new service established. Not that I think Linode is going to go under anytime soon. But you have to think about these things, and what exactly you're trying to accomplish. Me, I'll point my MX at my home server and hope my IP doesn't change (it hasn't in months) (no, I'm not using Linode DNS, for precisely this reason). I'm not running a business though.

_________________
The irony is that Bill Gates claims to be making a stable operating system and Linus Torvalds claims to be trying to take over the world.

-- seen on the net

Ah, the "my way or the highway" approach. From a service provider perspective I'd take the "too many roads; let's not bother" approach; let the customer do it themselves.

Too late. You lose all the benefits of performing these operations during the SMTP transaction.

_________________
Rgds

Stephen

(Linux user since kernel version 0.11)

There's two reasons to having backup MX; to handle temporary outages on your primary box and to handle more long term outages. You _could_ have a backup MX also at linode and be reasonably safe (seperate data center etc), unless linode goes titsup. In my case I have a second virtual server at Panix (similar setup, totally different company, network paths etc etc) for my redundancy

_________________
Rgds

Stephen

(Linux user since kernel version 0.11)