Spam issue of self-hosted email server

Hey folks,

I set up my own email server using mailcow, but the emails I sent kept being flagged as spam. I tried all possible settings but had no luck fixing the issue.

I’m curious to know if anyone else has encountered similar problems while setting up their own mail server and how they managed to tackle the spam problem. I’d appreciate any tips on how to overcome this issue.

Hi @serhattsnmz
Here’s some of the things you can try to solve emails being flagged as spam from your mailcow server:

  1. Ensure your domain’s SPF, DKIM, and DMARC records are correctly set. (if using use domain)
  2. Check if your IP is blacklisted and request delisting if needed.
  3. Warm up your IP by gradually increasing email volume.
  4. Use consistent sender information.
  5. Avoid using trigger words in emails.
  6. Monitor feedback loops and adjust based on responses.

These steps should help establish your server’s legitimacy and improve email deliverability.

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It does sound maybe like IP reputation. Possible. Check and IP and Domain Reputation Center || Cisco Talos Intelligence Group - Comprehensive Threat Intelligence.

In addition to what the poster above me has already said, you might need to check the reputation of your domain. I think tools like MXToolbox can help to check the reputation of your domain. You might need to remove outdated DNS records if your domain is flagged as suspicious to clean up.

I don’t actually recommend hosting a mail server for production use because it is challenging to maintain and can be costly. Instead, I would recommend opting for a privacy-friendly email hosting option like Migadu. While I would love to host my own mail server, it is not that easy.

I’m not sure where you are hosting Mailcow, but if you’re using a server provider, be cautious in your selection.

Firstly, avoid using a VPS server, as this increases the risk of getting blacklisted. Opt for a dedicated server from a provider that prioritizes infrastructure quality, such as Hetzner, in my opinion.

Secondly, be aware that major companies like Google and Microsoft may mark emails from your newly hosted mail server as spam, as the IP is new. To improve your IP reputation, there are services that enhance it by sending a considerable number of emails every day to your email and by receiving emails from your email. This helps Google recognize your email and IP as legitimate. I don’t have detailed knowledge of how these services work, but this is my understanding.

These seem to be the two main challenges for anyone attempting to host their mail server.


Thanks for the replies.

I have implemented all the suggested settings. However, the problem may be due to IP reputation, as you mentioned. I have not sent many emails and noticed that especially Google and Microsoft classify them as spam.

@ivansalloum I don’t understand why VPS servers increase the risk of getting blacklisted. Doesn’t a VPS server have a delicate IP address? Could you give me more information about why you suggest that?

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@ivansalloum I could not have said this much better. Agreed 100%. Self-hosting mass mail servers should be a last resort or under exceptional circumstances these days.

I manage one mail server for a client who sends about 500k emails in batches over weekends. But they started this over a decade ago. To do something like this now is extremely challenging.

Most reputable web hosts will block all email traffic on an IP after about 100 bounces and suspend and terminate the server for spamming after multiple (3-5) blocks within a short period (usually 24-48 hours). Some hosts are even stricter and will terminate after the second block.

Double opt-in is also the accepted standard, anything cold is generally considered a nuisance and in some countries is legally gray and others completely illegal. It’s very tricky and just better left alone. I don’t think most SMTP providers will even touch it anymore. Those days are over unless grandfathered in.

However, what I mentioned wouldn’t apply to @serhattsnmz as I assume he’s probably setting it up for more personal use and most likely the mail server needs IP/reputation warming up.

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VPS servers are more prone to landing emails in spam because they often share IP addresses. If another user on the same hardware engages in spam, it affects the shared IP’s reputation. Additionally, when you delete a VPS, the IP may be reassigned to a new user, potentially giving them a blacklisted IP. Dedicated servers have exclusive IPs and their own network, reducing these risks.

I completely agree with @hydn and @ivansalloum that setting up self-hosted mail servers can be quite challenging and not worth the effort.

I am feeling frustrated with the frequent changes in policies by email service providers. I have been using Yandex 360 for a long time but it has become difficult to manage my emails since they changed their policies. As a result, I migrated all my domains and emails to Google Workspace. However, recently Google decided to sell their domain services to Squarespace, leaving me uncertain about the future of their workspace policy, which also includes domains.

That’s why I tried setting up a self-hosted mail server, but it seems like overcoming the spam issue is not easy.

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Thanks for sharing your insights, @hydn! It’s always valuable to hear from someone with hands-on experience. Appreciate the input!

I highly recommend checking out Migadu. It’s currently the best mail hosting option for me. Migadu prioritizes privacy, and being based in Switzerland, they uphold strict policies. The service is very user-friendly. I personally use their micro plan with Outlook as my mail client, and it works seamlessly.

I just checked Migadu, but it seems to have email send/receive limits that I’m not comfortable with.

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I’m using postmarkapp for all of my projects (including notifications from this forum). There’s also: mailjet, sendgrid, mailgun, and a few others. See if any of them fit.

I find Postmarkapp has the easiest to follow UI that flows and makes things (setup) more logical.

I have been using Mailgun for a considerable period of time for both my personal projects and my company. However, I am aware that these services only offer mail sending and are used for SMTP integrations. I was wondering if you were recommending them as an alternative to Gmail or Hotmail?

You are correct. Only SMTP. I use gmail apps for inbox and I make use of catch-all. More recently, I’ve used Titan Email Service Suite for Professionals and Businesses Not free but low cost.

Hope this helps.