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

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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 ...
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 ...
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 ...
72
votes
9answers
43k 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 ...
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 ...
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. ...
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' ...
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 ...
0
votes
1answer
3k views

I can't send email from my server to gmail addresses

I'm using postfix, and have setup spf, dkim, and domainkeys. I can get my email to go to Yahoo, but not gmail. Here's the headers from an email send to Yahoo. Yahoo reports the email as domain key ...
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 ...
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 ...
3
votes
3answers
2k views

How do I spamtrap with Postfix?

How do I setup spamtraps with Postfix so clients that send to trapped addresses are prevented from sending me more spam?
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 ...
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 ...
4
votes
6answers
3k views

Send email on behalf of clients

We're a communications company primarily doing printing of statements / utility bills, then mailing them out in the post. A few clients have asked for e-Delivery. Pretty much take the print output as ...
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 ...
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 ...
5
votes
2answers
11k views

Postfix check outgoing mail for spam

How can I force postfix to check (and log/flag/etc) all outgoing mail for spam? Just want to make sure I'm doing my part on my servers. EDIT: Postfix config, as requested. main.cf # See ...
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 ...
4
votes
2answers
2k views

Barracuda tagging email with 'date grossly in the future.'

I have a Barracuda 300. Granted it's running on some old firmware and the Energize updates are quite outdated. I'd like to update them, but, not my financial decision to do so. Starting around the ...
4
votes
1answer
769 views

How to stop backscatter email spam

I know I can't do anything about people spoofing my email address, but what can I do about all those annoying bounce-mails? I get 5-10 "Undeliverable mail" a day, but I don't know how I can filter ...
3
votes
2answers
3k views

How do I throttle outbound email with sendmail

I know, I know, I should switch to Postfix. But in the meantime, how do I throttle outbound email (especially email to a single domain) in Sendmail?
3
votes
2answers
254 views

Dealing with referrer spam

One of our primary webservers, which runs Apache on Ubuntu, is coming under attack from heaps of referrer SPAM requests lately. There's enough of this that it is really sucking up our internet ...
2
votes
1answer
3k views

Is there any way to see why Outlook's client junk mail filter is marking a message as spam?

I have some users running Outlook 2007 connected to an Exchange server, and they're complaining about mail ending up in their junk box. There's no X-SCL tag in the mail headers so this filtering must ...
0
votes
5answers
2k views

Barracuda spam filter alternative - virtualization/appliance friendly?

I've sold and deployed Barracuda spam and web filters for years. I've always thought that the functionality was good (Barracuda Central, easy interface, effective filtering), but the hardware on the ...
3
votes
4answers
308 views

Minimize the chance my email is blocked/filtered as spam

I'm running a web-based store where order confirmations are sometimes blocked and don't reach the intended user. The structure of the business model is such that our product is marketed to the ...
1
vote
2answers
726 views

Postfix sends email to spam (gmail, hotmail)

I recently installed a postfix + dovecot + dkim multi domain, multi user, multi alias mail server on my debian squeeze system. Everything works except for one big issue that basically makes the whole ...
0
votes
1answer
139 views

Spam coming from domain, but from a user that I don't have [duplicate]

Possible Duplicate: How to stop people from using my domain to send spam? I have google apps handling the email for my domain (musikpitch.com). Some Cialis spam got sent with the email ...
0
votes
2answers
447 views

Adding spam addresses to SpamHaus and SpamCop DNSRBL

I have a Postfix e-mail receiving server setup. I have applied the following setting in my Postfix main.cf file: smtpd_recipient_restrictions = reject_unauth_destination, reject_rbl_client ...
-1
votes
1answer
487 views

Hotmail blocks company emails, when hyperlink is inserted in the message body [closed]

I received the following results: ========================================================== Summary of Results ========================================================== SPF check: pass ...
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
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 ...
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 ...
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 ...
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 ...
7
votes
5answers
6k views

Is there any alternative to SpamAssassin? [closed]

I'm looking for an alternative to Spamassassin. Anyone tried rspamd ?
5
votes
6answers
8k views

Emails going to Junk for Hotmail recipients [duplicate]

We send daily mass emails to our customers (~30,000+ emails per day). We have problems with Hotmail users receiving our emails. Sometimes the email goes to the Junk folder, but often it will got to ...
1
vote
4answers
2k views

Prevent spamming [duplicate]

How to prevent spamming in Cpanel / Linux server ?
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 ...
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: ...
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 ...
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 ...
5
votes
4answers
2k views

How do you test a new email filtering system?

What method do you use to test or evaluate potential new email filtering systems before you set it up on your production network? I am particularly interested in methods that are appropriate for ...
5
votes
2answers
903 views

Workaround SpamAssassin Y2K10 Bug (Mac OS X Server)

Bug Report: https://issues.apache.org/SpamAssassin/show_bug.cgi?id=6269 It turns out that SpamAssassin is adding a score of 3.2 (FH_DATE_PAST_20XX) to all email going through my mail server (Mac OS X ...
3
votes
3answers
1k views

How do I prevent mail from my Exchange server from being blocked?

Recently one of our client machines was infected with a virus and I believe was spamming addresses in the user's contact list. Since then our server has been appearing on blacklists and it has been ...
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 ...
3
votes
5answers
229 views

What Security Suite to choose?

What security suite would you recommend in an environment consisting of roughly 120 PC's and some 30 servers? Environment is MS only, so Exchange and ISA must also be supported.
2
votes
1answer
4k views

Postfix: Gmail marking my email as spam

I'm been trying to understand why Gmail is treating the email sent from one of my domain/server as SPAM. I found a lot of threads here about this issue, however I checked the usual suspects like ...
2
votes
2answers
1k views

How to limit the From header to match MAIL FROM in postfix?

SMTP clients are required to pass user authentication before sending emails to other domains (relay). And we can use smtpd_sender_restrictions to make sure the MAIL FROM address matches the ...
2
votes
5answers
7k views

Open Source or lower-cost alternatives to Barracuda Spam Filter

I'm aware of SpamAssassin-based solutions, but I'm looking for a free or low(er) cost spam filtering solution that's similar in functionality to the Barracuda Spam Filter. The Barracuda works well, ...