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Questions tagged [spam]

Unsolicited e-mail, comments or posts, often sent out in large volumes; possibly but not necessarily commercial in nature

Spam can refer to:

  • Junk e-mail
  • Unwanted posts on a website
  • Unwanted comments on a post on a website
  • A large number of posts designed to crash a system rather than provide useful content

For our canonical Q&A about how to prevent email you send from being flagged as spam, see How to send emails and avoid them being classified as spam?.

1396 questions
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Delete from mailq where subject matches

I have a mailq which is getting backed up with multiple emails with the same subject line. I would like to delete all emails in the mailq that match a particular subject line so they don't get sent. Any ideas how to do this? Pretty urgent as its…
David
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How do I remove IP from sorbs.net blacklist?

Our email server has ended up in the sorbs.net blacklist and we're going round in circles trying to get it removed, currently this is causing down-time between our suppliers. I am a developer and not familiar with Sorbs but asked if I could take a…
Brett Ryan
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Postfix, how can I reject spam from unknown IP (no DNS)

Despite all efforts to filter spam, I'm still getting spam from unknown even after I've set main.cf to not allow it and to check the DNS etc. Even after adding a pcre: to REJECT /.unknown./ some of them still get through and I don't understand why!…
Alienizer
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Postfix emails detected as spam with gmail

I know that there are a few posts about this and I have been reading them for a while now but still, I can't resolve my issue. I’m running ISPconfig with postfix and I can’t figure out why my outgoing emails are marked as spam in gmail and…
DamDIT
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Postfix reject_unknown_reverse_client_hostname: replace default unknown_client_reject_code (450) to 550. Why/When I should not?

In the daily battle against SPAM, there have been several times when I've been tempted to heavily enforce DNS requirements from clients connecting from the wild Internet. In detail, I would have added the reject_unknown_reverse_client_hostname…
Damiano Verzulli
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Microsoft is blocking mail from entire netblock. ISP doesn't know what to do?

I recently moved a client from basic T1 service to a multi-site MPLS solution with same vendor. The ISP, XO Communications, provided a decade of stable service as a T1 provider. The process of moving to the MPLS was a bit rocky and involved an IP…
ewwhite
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How do I configure SPF for multiple domains on a server? (also allowing gmail as a sender)

SPF (Sender Policy Framework) seems like a good way to combat spammers/spoofing. However, despite reading the explanations several times, I'm not quite understanding how to configure it correctly. Let's say I have my server at a.x.com which hosts…
Peter Boughton
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5 answers

Recommendations for SMTP services for massive mailing

What is the recommendations for SMTP services for massive mailing? Let me clarify, most of the free SMTP services (Gmail, Yahoo, Hotmail, etc...) has limits about the amount of messages you can send in a day. Gmail, for instance, only allows you to…
Daniel Silveira
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2 answers

Avoid creating backscatter on a Postfix forwarding server

I run a Postfix server that hosts a small, alias-based mailing list. Let's say people@myserver forwards to alice@someprovider and bob@someotherprovider. Now, alice@someprovider might use a more restrictive spam filter than I do. When a spam mail…
Heinzi
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How to report spam to blacklists

Is there a central place to report spam to various blacklists ? I regularly report to spamcop, but I do not see the addresses I reported as listed. (I guess nobody else bothers with my regular spammer. After being frustrated with bayes and…
hayalci
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7 answers

Does SMTP greylisting a) stop much spam and b) stop much legitimate mail?

I've just set up an SMTP server on a relatively little used domain using Postfix and enabled greylisting with SQLGrey. So far it seems to be working OK, and while there's the slight irritation of delays to emails from new senders, I can see from…
Whisk
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2 answers

Why an empty MAIL FROM address can sent out email?

We are using Smarter Mail system. Recently, we found that hacker had hacked some user accounts and sent out lots of spams. We have firewall to ratelimit the sender, but for the following email, the firewall couldn't do this because of the empty FROM…
garconcn
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Setting up a fake email address to trap spammers

I have heard it suggested that we set up a special email address, with it's only purpose being to be harvested. Then blacklisting every sender that targets this address. I'm wondering: if anyone else has tried this how do you go about doing it (ie…
Brent
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How does DKIM work when sending emails from multiple sources/servers?

So if I'm understanding DKIM correctly, it basically is a public/private key type of service. However, how does this work if you send emails from multiple servers/sources? For instance, I have a split domain where I send some emails (under the…
Marc NJ
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Does order of UFW rules matter?

When I first initialized my ufw, I did ufw default allow outgoing ufw default deny incoming ufw allow 80/tcp ufw allow 22/tcp Over the last week or so, I've been going through my access logs and banning IPs that are making malicious requests on my…
Thank you
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