1 yr. ago • 92%

SMTP Relay for monitoring - custom domain

Hi there,

what SMTP relay's / services do you use or can recommend for sending monitoring alerts.

I'm running a few services, but mostly all my custom scripts, and tasks are configured to sent an e-mail if something goes "off-script". Before I used my gmail account - but I'm in the middle of migrating away, and my requirements have evolved.

I've searched but I haven't found anything good. Services like Mailgun, Mailtrap etc. are nice - but their bundle's are a bit much for my taste.

The service/ relay should meet the following requirements.

bring your own domain (use your own domain/ or sub-domains as sender address)
must have DKIM (anything else is not a serious service!)
support SMTP via TLS
support multiple SMTP clients, with each different credentials/ secrets
Allow custom header/ envelope changes

At the moment I'm looking at Amazon SES, because I don't expect a lot of messages (I had 3 alerts in the last 1,5 yrs).

21 comments

I’ve been using SMTP2Go at work for our low volume of notifications and it works fantastic

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- Even if it's a bit different. It's always nice to see what's out there. I will definitively look into it.
  
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- For everything else you have SMTP to Apprise
  
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I am in the exact same boat. I just switched to Proton as it looked like they had these features right away. But it turns out you have to explain what you want to use smtp for before they allow you to generate tokens. Which is probably due to them attracting a high amount of scammers due to their really good privacy. So I can understand but it is a tad annoying. If you are willing to wait I'd give them a try. Their business plan is cheaper than googles and gives you a lot and they are open source.

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- Good to know, thank you. I looked into proton for my primary mail account, but I didn't think of it for that purpose.
  
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  Nevermind. After days of back and forth with them they said that they only have that feature available to big companies that have an account with them for a year or more, which is definitely annoying. I'm going to give Brevo a shot next, I heard someone mention them in a thread before about this. It looks like their free tier allows for 300 emails a day. I'll let you know how that goes if you are still looking.
  
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I use mailrise which is apprise under the hood for anything that doesn't have Pushover support built into it. Mailrise converts any email it receives to a push message. It supports a ton of different services like Pushover.

https://github.com/YoRyan/mailrise

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SES is pretty solid and easy to work with. Free for small email volumes like your use case.

You need to verify your domain and request production access explaining your use-case. If you're only sending to known recipients, you can just verify them and not worry about the "production access".

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- A little note on that: Amazon SES free tier is going to change starting tomorrow though. It changed from free to free for 12 months (with adjusted limits), see https://devclass.com/2023/06/23/aws-to-remove-62000-message-simple-email-service-always-free-tier-from-august-2023/
  
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  After the pricing change, I believe it's still free (or negligible) for low email traffic.
  
  5,000 emails per month are still free, at $0.07 per 1,000 after that.
  
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I use Purelymail for mine. I have Uptime Kuma integrated with it using the SMTP server and also have different things like my password vault connected through it. It's generally lightning fast and budget friendly too.

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- It sounds very promising.
  
  Thanks. I really appreciate all those “niche” products. With just web research I wouldn’t have found it.
  
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Have you thought of self-hosting mailcow? https://github.com/mailcow/mailcow-dockerized

It's very easy to set up and fairly straightforward to maintain, if you have a static IP and it's not impossible to get a PTR record then I highly recommend it. Yes you're self hosting your own mail server but mailcow vastly simplifies this.

Alternatively plonking it on the right VPS can also work.

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- I thought about self-hosting, but first of all I got a dynamic IP. Further I want a solution which has roughly 98% availability and 99,99% reliability, because this service tells me if everything burns/ goes awry. That's not the service I'd like to "toy" with. And hosting any kind of mail service with 98% availability and 99,99% reliability, automatic DKIM roll-over etc. is a tough nut. Even VPS cost's seem higher than just Amazon SES.
  
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For alerts I just have the server directly send email over SMTP to my address, no service needed. You could implement DKIM with such a setup if you wanted to.

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- Sure - but that would be another thing to self-host - because I have at least 5 machines which need to send, and I have a dynamic IP address - so it would involve updating the MX records via DNS API for at least 5 sub domains.
  
  To be honest, I'm a KISS kind of guy - not everything technical possible or imaginable is worthwhile. Especially if it's such a crucial part like alert monitoring. I want it done simple, secure, without caveats and keeping the complexity on the lowest level possible.
  
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  Most distro provide either EXIM or Postfix installed by default, and configured to send outbound emails from localhost. All you need to do is start the service, change /etc/aliases to add root: and run newaliases.
  
  You don't need MX records for that. MX is only needed to receive emails on a domain. Worst case is your monitoring emails will end up in spam (because there's no SPF configured for your machine), but your spam filter will eventually accept them as you move them from the spam folder to inbox.
  
  Pretty KISS in my opinion. More than changing all your apps to use an external relay, setup accounts, yada yada...
  
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I use mailgun at the moment. Still free for me and I send 2-3 mails per day. I had problems once with some mails not arriving or landing in spam, but that was fixed after a day or so.

Edit: Just checked the dashboard and I'm getting 1000 mails per month for free. Can't find exactly where they offer this plan anymore though, so they might have removed that.

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- Was signed up there as well, when they started like years ago. But I couldn’t get back into their free tier.
  
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