Emails Being Rejected as Spam

I have been getting this response to some messages sent to a long term recipient.

This is the mail system at host I'm sorry to have to inform you this message classified as spam-suspected and not delivered to recipient
I called my ISP(?) who said they fixed it, but they didn't.
Any suggestions where it is coming from?


  • Do you send email from your ISP's free email account? Personally, I would never do this. I know people that switched ISPs and ended up losing an email account they used for 20 years (or had to pay to continue using). I would use Gmail or Outlook, two free email services that are more likely to start charging money than disappear overnight.

    If you by ISP you mean "webhost", then that's also a no-no for hosting business email these days (well at least with an incompetent company like Netregistry). Microsoft 365 and Google Workspace have a near duopoly on the email sector, partly due to the pervasiveness of free Gmail and Outlook accounts. If either of them say it's spam, it's spam (regardless of what another blacklist says, but should detect this). You can send an email to the address at to check if your email isn't configured correctly or you're on any domain or IP blacklists. (Your friend seems to use Crazydomains hosted email, which appears to use Halon, which should be better than hosts that do it themselves).

    Sometimes it's not who you are but what you write. If I include a link to and it's on a blacklist, the email can get sent to spam, even if the email is a warning about

    • Thanks. Using desktop Outlook and crazydomain on a company email address. domain has no issues at Spamhaus
      Mailgenius fails my domain suffix - Mailgenius just failed

      • +1

        Crazy Domains explains the domain. It sounds like it is a Crazy Domains issue.

        Personally, hosting business emails on POP/IMAP with Crazy Domains etc is very old school and always has more and more problems. I would suggest moving to Google Workspace, might cost a bit more but is well worth it. Less headaches.

      • Pretty much what geekcohen said.

        Just keep in mind that switching to Google Workspace won't necessarily solve a blacklisted domain. If your website is phishing, for example, mail servers (especially Google) will blacklist your domain.

        As an example. A client of mine had an old website that was never updated and suddenly disappeared off Google. His emails, hosted with Google Workspace (though it had different name back then), stopped getting through. It turned out that his website was hacked and a phishing page was setup as a fake bank link to steal credit card info. A cPanel virus scan revealed he was infected.

        The problem was that Google sent warnings to him that his emails weren't getting through, but they ALSO went to spam since they had his banned domain name in the body of the email! After moving to a new host and starting fresh (just to be safe), from memory we had to request that Google "reconsider" the domain via webmaster tools.

        • Thanks. I use Google Workspace for another business, and hate it. Being old school, I like to have my data in my building.
          Probably will go back to Crazy. It is only one email address that bounces.

          • @GOFYS:

            I use Google Workspace for another business, and hate it.


            Being old school, I like to have my data in my building.

            Get a VPS for your email hosting then? Then you are in control.

          • +1

            @GOFYS: If it's just one email address regardless of the message content then it's possibly the long-term recipient's email address causing the issue. If the recipient is jimmydealer @ then the domain itself may be triggering the spam block (like my example above). Or the subject matter for that recipient is something spammy like viagra, cialis, anabolic steroids etc.

            • @peterpeterpumpkin: Sorry, it's a hotmail address.
              Some of the language and topics might be objectionable in public, but it's been the same for years.

      • Do a SPF check on your domain on the link below. If there's no SPF record setup in your DNS then you will have issues emailing a lot of people. Gmail for example will put emails into the Spam folder if the sender does not have a SPF record.

        • Did that. 10 green ticks.
          Brain starting to hurt.

  • -1

    You have given very little information for anyone to be able to help you. The issue could be on your end, could be on the receiving end or anywhere in between. If this is a company email address, do you have IT support that can help you?

    • -1

      Read the comments because some of those questions have already been said.

    • Thanks, I don't see it as an IT Support thing. Everything works fine, just one regular email recipient inconsistently bounces with the spam message.
      In fact the last bounce was a reply, it had one four letter word in it, but otherwise straight business topic.
      Crazy domains said they fixed it a week or so back, gave me a completely incomprehensible explanation, and now it's back.
      There's an OZB person out there who knows.

      • I didn't realise it was a single recipient. Are they using a mail service like Gmail or their own domain? I know some mail services like have strict antispam requirements where having an SPF record isn't enough.

        • hotmail

          • @GOFYS: Trying to send any attachments?

  • No

  • I am now experience identical problems with any email sent to a hotmail address with an identical bounce message also using crazydomains

  • As others have touched on, make sure you have DNS SPF records setup… having said that hotmail is known to have temperamental spam filtering :p

  • Oh my gosh, I have this problem and it has been driving me absolutely bonkers.
    I tried Googling months ago with no luck- just did again and this has happily popped up!

    I'm also using Outlook and hosted by Crazy Domains.
    I've also contacted them previously (multiple times) to troubleshoot, and they keep telling me they've 'fixed' it, but the problem continues.
    Pretty much every email I receive that's junk/unknown sender also arrives with a 'postmaster' halon.ds email. Some mornings I wake up at have 50 emails- 25 junk, 25 postmaster.
    I have an SPF record set up.

    • Contact Crazy Domains to get their help. They are your provider, so they should be helping.

      If not, I would suggest moving. Using something like Google Workspace is often a better solution. Using POP3/IMAP with a shared hosting provider is becoming more and more of a problem. I always suggest people use a better solution like Google Workspace or Microsoft 365. Google Workspace is my preference.

  • I'm getting the same issue with crazydomains…

  • Sorted out. Crazy Domains is checking specific "words" in emails.

    Try breaking down your problem email and sending it in bit's until one bounces.
    That will be the offending "word"
    It looks like they may be experimenting with big Brother control of what you can send.
    and if they are doing it, so are others.

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