Monthly Archives: September 2023

Hosting E-mail @ Home

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Having been in the ISP and hosting industries from roughly 1996-2014, living through the transition of mail servers from being something that everyone runs themselves as a matter of course to a nightmare of spam, block lists, and becoming the favorite entry point of threat actors that any rational person and company chooses to outsource to entities with far more resources to dedicate to the challenges, I’ve long scoffed at people who want to run mail servers at home.

Your ISP, the providers of mail services large and not-so-large, and the purveyors of block lists and anti-spam/threat gateway services all want to make this very difficult for you. Deliberately.

People find a way, often using the free tier of some bulk mail sending service to route their outbound mail, or perhaps getting lucky DIY-ing it with a VPS provider who has managed to keep their IPs off the naughty lists.

I prefer not to be a freeloading non-paying customer of anyone, as “free” services and “free tiers” over time tend to become more restrictive or disappear, and I know it’s foolish to believe any VPS provider that allows SMTP traffic isn’t going to eventually have a block list go nuclear on their entire IP space, so I’ve long chosen to pay Microsoft for their lowest-cost o365 account to have e-mail for my own domains and I think the $6/m or whatever is a fair price to pay.

But I’ve had this theory that one could use Microsoft’s Exchange Online Protection Plan, which costs just $1/m* per user, to cheaply avoid many of the pitfalls of self-hosting e-mail servers. Today I put it to the test with a domain I’d registered last week. Partly to prove the point and partly for the opportunity to mess around with Synology Mail Plus.

It absolutely worked. Here are the steps I followed:

  1. Installed Synology Mail Plus.
    • Configured for my domain.
    • Activated a single user.
    • Configured SMTP Smart Host pointing to my VPS over a VPN tunnel.
  2. Configured port forwarding and firewall rules to only allow TCP/25 connections to the Synology from o365 IP ranges.
  3. Clicked ‘Buy Now’ at Exchange Online Protection Plan.
    • Created a new o365 tenant account.
    • Handed over my credit card info for the $1/m charges.
  4. Added my domain to o365 tenant.
    • admin.microsoft.com -> Settings -> Domains.
    • Let Microsoft make the changes to my Cloudflare DNS.
    • Adjusted the automatically created SFP DNS record to include my VPS IP, along with my static IP for completeness.
  5. Change the Domain Type to InternalRelay.
  6. Created Connectors for Inbound and Outbound e-mail.
    • admin.exchange.microsoft.com -> Mail Flow -> Connectors.
      • For Inbound I have a static IP and port 25 isn’t blocked, so I configured that to connect directly to my mail server.
      • For Outbound I am blocked on port 25, and for the purposes of a Connector there are no alternate port options, so I proxy through the VPS using nginx.
      • Outbound requires either having a static IP or using a certificate for auth. I went with IP auth.
  7. Enabled DKIM
    • security.microsoft.com -> Policies & rules -> Threat policies -> Email authentication settings -> DKIM
    • Added DKIM DNS records.
  8. Added DMARC DNS record

Microsoft could do a much better job of unifying all these different administration portals, but overall it wasn’t that bad. I tested by sending an e-mail to my Gmail account and it was successfully delivered to my Inbox, having passed SPF, DKIM, and DMARC:

Image of Gmail "Original Message" view showing that SPF, DKIM, and DMARC all passed for a e-mail received from my home e-mail server.

And, mind you, this was a first message from a domain on a less-common .TLD, registered days ago with no prior reputation.

$1/m* seems pretty cheap to ride on Microsoft’s coattails for e-mail delivery, along with getting 1-day of inbound mail spooling, plus whatever value Exchange Online Protection provides as an anti-spam gateway. It’s not abusing the service in any way — this is what any cloud-based anti-spam service needs to function. EOP is special because Microsoft o365 services don’t have monthly minimum charges.

Of course, there are providers out there specifically offering inexpensive inbound MX spooling and outgoing SMTP relay services to the frugal self-hoster. Dynu, for example, is $9.99/yr per domain and service.

I might be halfway to talking myself into bringing all of my e-mail home. For my collection of domains and potential user count, EOP is dirt cheap.

* Plus the price of a VPS if dealing with port blocking, but we all need a VPS for something anyways, right? And that EOP license is “per user” but Microsoft won’t know how many users you have unless they ask you / audit your o365 licensing, and “Yep, just the X, it’s just for me [and my X-1 family members / friends / employees], and EOP is the only service needed right now” ought to be a perfectly acceptable response.

De-container-ification

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I’ve been on a slow slog to remove containers from my home and remote UDM Pro and UDM Pro SE so that I’m not trapped on old firmware, but I finally got it done. It sucks that UI chose to remove podman entirely once they decided to stop using it. Let that serve as a reminder that today’s UI isn’t the hacker-friendly Ubiquiti that so many of us fell in love with.

Finally having seamless site-to-site VPN via Site Magic sure is nice tho. If they had a way to integrate non-UniFi gateways it could be a full replacement for my ZeroTier tunnels but I doubt that’ll happen. I might go back to running ZeroTier directly on my routers since they both now have apt, as I liked having one central place to manage all the inter-site routing.

Synology, Part Deux

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Dave Jansen’s Synology DS920+ Final Impressions has some insight into why a Synology may not be a great alternative to DIY for those who are reasonably technical. I was fortunate to be gifted a very old Synology that was destined for e-waste disposal so my approach has been to figure out if it was good enough at anything to be worth not just taking the drives and disposing of it, as opposed to buying based on the marketing hype and discovering the hard way that it doesn’t quite live up to expectations. Worst-case for me was that I’d have overpaid a few bucks on shipping.

Amazon has been putting the DS1522+ on sale for $579.99 so I decided to go ahead with that plus the 10GbE card and a pair of 512GB Samsung 970 EVO Plus for cache. It stings but for me the value of Active Backup for Business alone makes it worth the price over a timespan well under the 3-year warranty period, and Synology’s track record is such that I expect its useful life should extend until at least 2029. Zero percent financing for 12 months on my Amazon VISA soothes the immediate pain to my wallet.

A week in and I’m pretty happy with that decision. Local incremental backups of my laptop, four servers, and 10 VMs, running simultaneously, now finish in under 10 minutes — inconceivably fast compared to what I was used to with my previous urbackup setup. For giggles I decided to see how well it could handle backups of the mini PC at our cabin running Hyper-V and four VMs over a VPN that can manage about 3.5Mb/s upload. Took a whole-ass day for the first pass but now the dailies are running around 1:45, which is an absolutely acceptable window for hogging all the precious upstream during hours when nobody should be awake.

The kids’ laptops remain a challenge… but reality is that it’s hard to care that much. They probably don’t have any / much data worth caring about that isn’t in a cloud somewhere. And eventually they’ll learn to appreciate backups the hard way, like our ancestors have done for centuries.

Next I need to figure out backing this thing up off-site to our cabin. Backups of my backups. Because if a fire can take out all of your original data along with the backups, it’s not that great of a backup. There’s no good space to put a 2U RackStation, and truth be told, I don’t want to leave anything there that would inconvenience me to replace because it goes unoccupied for long periods and it’s meth country.

Might be a good use case for one of my retired HP Microserver Gen8 systems with MinIO as an S3 backup target for Hyper Backup. Or going dirty with Xpenology. TBD.

In the meanwhile, I’m slowly exploring more of what DSM has to offer. I’ve started using Synology Photos to backup my iPhone camera roll, which is the single biggest feature that has kept me attached to Dropbox. From that perspective, Photos does all that I need. Facial recognition and object classification range from underwhelming to hilariously bad, but those aren’t features I care all that much about today.

(In my dreams, Synology Photos, or PhotoPrism, or any of the other open source alternatives would have an integration for Google Vision AI and/or Amazon Rekognition — they’re reasonably affordable at the “80% of every photo and video I’ve ever taken is presently on my phone” scale)

I’ve also got Cloud Sync doing its thing with my Dropbox, Google Drive, and OneDrive for Business accounts. That’ll replace having it shared out from my former backup server VM. And I’ve consolidated the rest of my file shares — they don’t see much use, but getting them all in one place is… something entirely unimportant me. DSM makes that all much more pleasant than TrueNAS tho.

Synology Drive Server is next on my exploration todo list. Because I’ve been wanting to stop paying for Dropbox for a long time but it’s hard to fight against the inertia and all the little ways that Dropbox burrows itself into your life. In the general everyday sense my needs are so basic that literally anything that reliably syncs files and has an iPhone app is an adequate substitute, but I have a few apps that use Dropbox to sync settings/data across devices, and a few things that perform their own backups directly to Dropbox. I suspect that some of them will be stuck on Dropbox and I will have to come up with a process to stay under the free tier limits.