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

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72
votes
9answers
42k views

How to stop people from using my domain to send spam? [duplicate]

I receive Mailer Daemon messages saying certain emails fail. My domain is itaccess.org which is administered by Google apps. Is there any way I can identify who is sending emails from my domain, and ...
65
votes
9answers
75k views

Dealing with HTTP w00tw00t attacks

I have a server with apache and I recently installed mod_security2 because I get attacked a lot by this: My apache version is apache v2.2.3 and I use mod_security2.c This were the entries from the ...
63
votes
6answers
24k views

Fighting Spam - What can I do as an: Email Administrator, Domain Owner, or User?

This is a Canonical Question about Fighting Spam. Also related: How to stop people from using my domain to send spam? What are SPF records, and how do I configure them? There are ...
43
votes
6answers
74k views

How to send emails and avoid them being classified as spam?

This is a canonical question about how to handle email sent from your server being misclassified as spam. For additional information you may find these similar questions helpful: Best ...
40
votes
4answers
5k views

Is greylisting still an efficient method for preventing spam?

I've used greylisting on my servers for many years, but I don't know how effective it is nowadays. Is it still good for fighting spam in 2012? Or is the typical spammer MTA capable of resending ...
30
votes
7answers
3k views

How can I attract more Spammers hitting my Spam traps?

Currently I have a number or domains that are set up as Email Spam traps. So if I get mails on that domains I can be certain that it is ~100% Spam. I'm using this information to temporarily defer ...
27
votes
7answers
3k views

Why is it a bad idea to use a customer email as the from address

I've got an application that emails users once they have filled in a form. It uses a no-reply@customerdomain.com as a from address. The customer wants it to use the email from the form as the from ...
27
votes
4answers
679 views

What happened to all the spam?

Don't get me wrong, I'm mostly glad that this happened. However, I want to make sure that the reasons for it happening are sound - rather than there being a problem with our methods. I'd like to ...
25
votes
7answers
15k views

How to stop spammers from sending spam as me

We've starting to receive bounced spam messages and the sender is one of our email address. We know that we don't send spam from that address. We've tried changing the password but we're still ...
21
votes
4answers
7k views

Best Practices for preventing you from looking like a spammer [duplicate]

I'd like to feel more confident setting up mail for my clients with regards to false positives. Here's what I know: SPF records are good, but not every spam filter service/software (SFSS) uses ...
19
votes
4answers
2k views

What are the best methods for catching snowshoe spam?

I'm using Smartermail for my small mailserver. We've been having a problem lately of getting waves of snowshoe spam that follow the same pattern. They come in batches of 3 or 4 at a time. The ...
18
votes
7answers
9k views

Why do 'hackers' setup bots repeatedly fill out web forms?

There is something I don't get, one of my web apps has a small form that allows you to enter you name and email address to "subscribe" to a user list for a site I maintain. The site is very low ...
17
votes
4answers
55k views

Fixing My MTA's Poor Reputation

I have a web site that needs to send email to customers to deliver files that they have purchased. Reliable email delivery is vital to this business. Unfortunately, most of the emails sent by my ...
17
votes
9answers
2k views

Gmail and Live are making all messages from my server as spam

I'm getting very weird results here. When my server sends an email to my @hotmail or @gmail account, it's marked as spam. When I send email through my server from Outlook to @hotmail, it doesn't get ...
16
votes
3answers
2k views

Is my new gTLD causing it to get filtered as spam?

I have a domain called "*******.international". I decided to go with the new gTLD because it fits the name of the company pretty well. I have an automated emailer setup to send emails to our clients' ...
14
votes
11answers
16k views

Good & free Exchange spam filter [closed]

Do you know a good (and free, if possible) Microsoft Exchange 2003 spam filter?
12
votes
10answers
3k views

Using fake MX records to combat spam

I have a client that is getting heavily spammed.. It's the 15th of the month and POP3 bandwidth is almost 100 GB. There are only 7 e-mail accounts on this domain. I installed SpamAssassin set it to 5 ...
11
votes
2answers
708 views

How can I reduce the damage of stolen mail accounts?

Currently I’m offering some webhosting to a few advertising agencies for their premium customers. But currently I have a great problem with the E-Mail Service. In the last week, the E-Mail Accounts of ...
11
votes
3answers
4k views

Gmail rejects emails. Openspf.net fails the tests

I've got a problem with Gmail. It started after one of our trojan infected PCs sent spam for one day from our IP address. We've fixed the problem, but we got into 3 black lists. We've fixed that, ...
10
votes
10answers
2k views

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 ...
10
votes
7answers
2k views

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 ...
10
votes
3answers
3k views

How I stop spam backscatter rendering email on my domain unusable?

Some miscreant is using non-existent accounts on my domain as a forged sender for spam emails (i.e., sdfhdfsg@mydomain.com). All the out-of-office and spam rejection emails are coming back to me ...
10
votes
1answer
344 views

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 ...
10
votes
5answers
8k views

How to minimise SpamAssassin (spamd) memory use

I'm using SpamAssassin on Debian (the default configuration with Pyzor, AWL and Bayes disabled, and sa-compile enabled), and each of the spamd child processes consume around 100 to 150MB of memory ...
9
votes
13answers
10k views

Relatively easy way to block all traffic from a specific country?

I know this sounds terrible, but I have a web app that has no users in the Philippines, but is constantly bombarded by spammers, carders testing cards, and other BS from there. I can see in the logs ...
9
votes
2answers
22k views

How do I check a reverse PTR record?

I need to check a reverse PTR record to make sure that a script I have is sending emails which will actually received by my users and not incorrectly marked as spam. I understand that the ISP which ...
9
votes
5answers
13k views

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. ...
9
votes
3answers
248 views

Email from our server tagged as junk by Hotmail Smartscreen unable to inform Hotmail that it is legitimate

Since more than 1 month ago we are having our email from one of our servers systematically tagged as junk by Hotmail Smartscreen filter. We have taken the following actions/measures without success: ...
9
votes
1answer
271 views

Is there a way to get spamassassin to score the top lines of a message body more heavily?

A lot of spam is getting through the filter on the mail server I run with the relatively simple trick of starting with few lines of (incredibly obvious) weight loss or other scam text at the top, ...
8
votes
9answers
9k views

My EC2 instance's email is being spam blocked by gmail

I'm not sure what to do about this. When on a different IP (the same server set up, domain etc), we had no problems with email deliverability. Since transferring to EC2, despite having the AWS imposed ...
8
votes
2answers
3k views

IIS7 ban IP range [duplicate]

Possible Duplicate: How does IPv4 Subnetting Work? I have a list of IP ranges I would like to ban, an example being: 119.30.47.xx Where xx is anything. I've added the domain and IP ...
8
votes
4answers
13k views

How does a Reverse DNS lookup work with regards to spam filters?

I have heard that most spam filters use a reverse DNS lookup on the originating IP address of the sending SMTP server (or something like that) as part of the verification process. I want to make sure ...
8
votes
1answer
8k views

What is preferable, “no-reply@” or “noreply@”? [closed]

Having a service that sends out notifications to users, I'm currently thinking about changing the sender email address from "info@" to something more meaningful. Since a reply never makes sense, I'm ...
7
votes
3answers
2k views

Should I let email bounce or send it to a blackhole?

I have a lot of unused (old, dead) accounts on my machine. Many of them receive literally thousands of emails a day, all spam. If the account was used by a person, I let the email bounce so that ...
7
votes
4answers
2k views

Why does my mail get marked as spam?

I Have the server "afspraakmanager.be". It matches everything not to be a spam server.(it isn't by the way): it has reverse dns, spf,dkim,... . But hotmail marks it as spam. I think the problem is ...
7
votes
2answers
3k views

GMail suspects confirmation email in stealing personal information

When user registers on my web site, web site sends user email confirmation link. Subject: Please confirm your email address Body:Please open this link in your browser to confirm your email address: ...
7
votes
4answers
6k views

What to do with an out-of-warranty Barracuda Spam/Web filter?

I'm working with an organization that would like to start using a old Barracuda Spam Filter 300 unit. I've sold and configured plenty of these, but was surprised to see that this unit's warranty ...
7
votes
3answers
136 views

Does “~all” in the middle of an SPF record signal the end of the record when it is parsed?

Our company's SPF record format is as follows: "v=spf1 include:_spf.google.com ~all a mx ip4:X.X.0.0/23 include:spf.example.com ?all" So we have an "~all" in the middle of our SPF record. On the ...
7
votes
1answer
2k views

Prevent mail being marked as spam

This is a canonical question about avoiding outgoing mail being classified as spam. I'm wondering how to prevent my emails from my site being marked as spam? I'm using sendmail. I'm trying to ...
7
votes
5answers
6k views

Is there any alternative to SpamAssassin? [closed]

I'm looking for an alternative to Spamassassin. Anyone tried rspamd ?
7
votes
4answers
4k views

SMTP message rate control on Ubuntu 8.04, preferably with postfix

Maybe I am chasing a bug but I am trying to set up a smtp proxy of sorts. I have a postfix server which receives all the email for a collection of servers/clients. It them uses a smarthost ...
7
votes
6answers
12k views

All my emails to Yahoo!, Hotmail and AOL are going to Spam, though I've implemented every validation method (works for Gmail though)

I've implemented everything and checked everything (SPF, DomainKey, DKIM, reverse lookup), and only Gmail is allowing my emails to go to Inbox. Yahoo, Hotmail and AOL are all sending my messages to ...
7
votes
1answer
502 views

Let Postfix handle spam in two ways

I've got postfix setup so that mail coming in from smtpd is automatically filtered through spamassassin (which reinjects it into the mailqueue with added headers) Now I want to do 2 things with ...
6
votes
4answers
1k views

How can I block outside mail FROM postmaster@mydomain.com?

A security firm has been testing my mail server and claims my Postfix daemon is an open relay. The evidence is as follows (valid public IP for mail.mydomain.com has been changed to 10.1.1.1 for ...
6
votes
12answers
2k views

Recommendations for handling Directory Harvesting spam on Exchange 2003

Our Exchange server is getting slammed with anywhere between 450,000 and 700,000 spam messages per day. We receive about 1700 legitimate messages in the same time frame. Roughly 75% of the spam is ...
6
votes
7answers
6k views

Equivalent to denyhosts, but for HTTP requests?

My web server (apache2) is continually pounded by malicious bots, asking for URLs like these: ...
6
votes
6answers
3k views

Spam prevention tips for Postfix [duplicate]

Without using SpamAssasin, or similar, what are your best tips for preventing spam. Please try and provide config examples :D
6
votes
2answers
2k views

Is the 10-DNS-lookup limit in the SPF spec typically enforced?

My understanding is that the SPF spec specifies an email receiver shouldn't have to do more than 10 DNS lookups in order to gather all the allowed IPs for a sender. So if an SPF record has ...
6
votes
2answers
1k views

Office 365 - what is in the “Sensitive Word List” for spam filtering?

In Office 365 you can toggle a few settings to help with spam email filtering. Among these is a setting to enable a "Sensitive Word List" as shown below: The problem is...I can't find any list on ...
6
votes
6answers
42k views

How do you detect a spambot on your network?

I help manage a small network of about 40 computers. We are running an Exchange 2003 mail server. What is the best way to find which machine is infected by a spambot? I've tried installing anti-virus ...