So I’ve been running self-hosted email using Mailu for a couple of months (after migrating out of Google Workspace). Today it turned that although my server seems to be capable of sending and receiving emails, it also seems to be used by spammers. I’ve stumbled upon this accidentally by looking through logs. This seems to have been going on for all this time (first “unknown” access happened just a couple of hours after I’ve set everything up).
While browsing the logs there were just so many crazy things happening - the incoming connections were coming through some kind of proxy built-in to Mailu, so I couldn’t even figure out what was their source IP. I have no idea why they could send emails without authorization - the server was not a relay. Every spammy email also got maximum spam score - which is great - but not very useful since SMTP agent ignored it and proceeded to send it out. Debugging was difficult because every service was running in a different container and they were all hooked up in a way that involved (in addition to the already mentioned proxy) bridges, virtual ethernet interfaces and a jungle of iptables-based NAT that was actually nft under the hood. Nothing in this architecture was actually documented anywhere, no network diagrams or anything - everything has to be inferred from netfilter rulesets. For some reason “docker compose” left some configuration mess during the “down” step and I couldn’t “docker compose up” afterwards. This means that every change in configuration required a full OS reboot to be applied. Finally, the server kept retrying to send the spammy emails for hours so even after (hypothetically) fixing all the configuration issues, it would still be impossible to tell whether they really were fixed because the spammy emails that were submitted before the fix already got into the retry loop.
I have worked on obfuscation technologies and I’m honestly impressed by the state of email servers. I have temporarily moved back to Google Workspace but I’m still on the lookout for alternatives.
Do you know of any email server that could be described as simple? Ideally a single binary with sane defaults, similarly to what dnsmasq is for DNS+DHCP?
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I use mailcow for self hosting.
Nowadays I’d recommend a simple postfix + dovecot setup. If you care about a web-UI and possibly some groupware functions put SOGo on top.
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I agree that a static IP address is an absolute requirement for a mail server to send messages these days. You also need a host of checks in place like SPF, DKIM, and DMARC, along with a strong set of blocklists and spam filters. My own setup includes dual ISP connections from two different providers, and even with all that in place, Microsoft has always been a thorn. They will block me for no apparent reason, their own tools don’t even show any detected spam activity, and sometimes they don’t even block the same IP address (or provider) that my emails were sent from. Every other spam service on the planet behaves in a rational way, but of course Microsoft has made a point of locking in so many businesses to their own spam-ridden service that you simply can’t run a mail server any more without being able to talk to them.
Overall, yeah it can be a pain to run your own mail server. I can’t imagine trying to use a pre-built mail server and expect it to run, there’s so much that you have to configure to each specific setup. It’s not like a web server where you load up a docker container and it just works.
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even when they are actually static
Are they often not ‘actually’ static? In what way?
Well… ok? I’ve only been running mine since around 2001, I guess I should give up?
Same, though I too switched to an aws instance and before that linode since 2008 or so.
Miss the old days of not having to worry about IPBL.
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I’ve had similar experiences trying to send mail to Microsoft-hosted email addresses. My current “solution” is to send all outgoing mail directly from my VPS-hosted Mailu server… EXCEPT for Microsoft-destined mail. For those messages, they get transparently relayed from Postfix to a third-party email sending service that Microsoft apparently trusts.
The upshot is I can still use my own Postfix daemon for all mail sent to sane (non-Microsoft) providers.
I’ve never heard of anybody relaying just the Microsoft e-mails, but that’s a really funny spiteful solution.
Lately I’ve been able to send to outlook just fine (maybe it’s just dumb luck, who knows). I think I had troubles initially because they’re really picky about rDNS matching the MX exactly. I also signed up for SNDS just in case, but I don’t know if they factor that in…
Ooh, lucky you! Maybe it was both the rDNS and the SNDS. Part of the problem IMO is it’s such a black box…
Definitely. It’d be nice if there was more reporting when a provider drops your messages.
In my experience (self hosting mail since 2005) signing up for SNDS does factor in. Although last time I had trouble with delivery to MS, my hosting provider Linode’s support also helped out by contacting MS back channels on my behalf. The biggest problem I (rarely) have is when whole IP blocks end up on a ban list that MS seems to really trust. That said, fuck it, I will keep fighting the fight and self host my mail like a stubborn old git :p
Hell yeah :). I’ve heard people have had problems with Linode’s IP blocks with MS… I’m glad to hear that Linode was actually able to help you resolve the problem. The biggest problem seems to be that you just might not realize if your e-mails are being dropped. Not sure if MS will notify you via DMARC if your IP block has been blacklisted, from the sounds of things they probably don’t and just silently drop things, so I guess you have to monitor the blacklists yourself?
unless you realllllly enjoy self hosting your email, IMO it’s just not worth it anymore with the state of things. I use Fastmail and could not be happier.
Same here. Gave up and went fastmail. Love em.
ProtonMail. 100%.
I set up custom DNS and catchall so yourcompanyname@saltycowboy.org is really how I filter spam.
Please note, saltycowboy.org isn’t really my domain.
So you’re saying it’s available? 👀
I’ve also done the same, it’s been great.
Protonmail. That’s what I use connected to my own domain.
I use fastmail, and I enjoy it a lot. Their masked email is very nice as well, and integrates with bitwarden. So quite convenient to use my personal domain for stuff where my identity matters, and use masked @fastmail addresses for more disposable stuff.
The only thing that ticks me a tiny bit is that their mobile app doesn’t have offline mode; but you can use imap client or w/e, so it’s not too much of an issue.
Also hear good things about protonmail; I would consider it if I didn’t already use/trust fastmail.
For mobile with fastmail, I use fairemail. Works great with it, and provides a nice merged view with my non-fastmail work emails.
Another vote for Fastmail. In my recent effort to degoogle I switched to Fastmail and I love it.
Throwing my hat in for Protonmail.
Personally using Ionos.
Not bad experiences so far but you need to watch out at times and check your invoices.Same, IONOS is cheap and I had no issues when requesting they open port 25 for my mail relay server.
I have used https://migadu.com/ for over a year now with no problems. Very happy with them. Setup is well documented.
Most reasonable pricing I’ve seen for a family use case.
Great configuration, very flexible and fill of features. They make it easy to get all the DNS records you need to add to your domains and they have a diagnostic tool that checks that everything is set correctly. They even include wildcard aliases (which I’m not sure if it’s mentioned in their public pages).
Should also note that they don’t limit accounts, domains, aliases or any features, just overall mails and storage space. The only additional limitation on the lite account is inability to set account quotas.
This was the provider I went with after self-hosting my mail for 7+ years on an OpenBSD VPS. I feel like Migadu is an honest and good-value service.
Additional: It’s paid, and you need a domain.
Edit: spelling
Mailcow dockerized.
I vote for maddy, but one important note for my setup: my family uses always-on VPN, so i only open port 25 for the world. Imap can be accessed only from vpn. In such case server can’t be used as relay from internet. Maybe try that way?
I am not saying your server is not secure, but just fencing off IMAP from the web is not enough to limit spammers from relaying mail through your server. They usually exploit a misconfigured SMTP server, which does run on port 25 (plain or start TLS mode)
That’s right, i’ve mixed two topics. Thanks for pointing that out
I use docker-mailserver with sendgrid as smtp relay
Just switch to mail in a box.
The answer bad self hosted apps isn’t less self hosting.
Step 1: cut a hole in the box
I found myself in a similar situation last year. MXRoute’s lifetime plan works well for those domains that just need basic email and not a lot of storage.
