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

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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
7k 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
3answers
7k views

Send spam mail to a special folder using postfix

I have a postfix server running amavis and SpamAssassin to help filter spam. Messages that are detected as spam look like this when delivered into the user's Maildir: From tom@tom-mint Fri Mar 15 ...
6
votes
3answers
11k views

Why is my SPF Record not working?

A spammer is using my domain to send spam, and I'm receiving a large amount of bounced email. I have an SPF record on the domain, however it doesn't appear to be having any effect. Receiving MTA's ...
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
3k 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
46k 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 ...
6
votes
2answers
319 views

Which DNS Black Lists would you recommend to discard spam in pre-queue?

There are many black lists out there, with bad and good reputations. Also, some people recommend to use RBL lists only in score-based systems (like spamassassin) while others (including commercial ...
6
votes
2answers
10k views

Optimal parameters set for Postfix “smtpd_recipient_restrictions”

we've inherited the DNS from another ISP and now our mail server is bombed by about 1000 emails per minute, 99.99% of these emails are just spam. We're trying to optimize the filtering/rejecting the ...
6
votes
2answers
282 views

DNSBLs for IPv6

Spamhaus and other well-known DNSBLs don't yet support IPv6, and I'm not sure they ever will. What alternatives are there for spam filtering on IPv6? One approach is to rely entirely on ...
6
votes
2answers
14k 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
1answer
555 views

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 ...
6
votes
2answers
619 views

Exim backscatter

One of my relays has been listed on backscatter.org, now I'm trying to configure our existing config only to send bounces to local users only. Does anyone knows how I deal with this issue? I've added ...
6
votes
1answer
53 views

How Does Low Volume Affect (esp. live.com) Email Deliverability?

I've been sending emails for years with out any serious reputational shocks, but with low IP volumes (no bulk mail or automated transactional email), even with multiple Domain names. My Gmail ...
6
votes
3answers
2k views

postfix skip spam checks for authorized SMTP

Is there any way to configure postfix to skip spam/antivirus checks for those smtp connections that are SMTP-AUTH'ed? I would like to keep all the standard checks for external smtp traffic, but for my ...
5
votes
3answers
3k views

PTR OK, SPF, DKIM passed but email messages are marked as Spam by Google?

# host 1.2.3.4 4.3.2.1.in-addr.arpa domain name pointer mail.domain.vn. # dig +short txt domain.vn "v=spf1 a mx ptr -all" # dig +short txt mail.domain.vn "v=spf1 a -all" Here's an email header ...
5
votes
2answers
5k views

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 ...
5
votes
2answers
1k views

Will blocking port 25 on a router cripple outlook clients?

I work at a small ISP, we manage about 60 buildings with p2p radios and a main cisco router at a central location. Recently we were notified that a phishing domain is associated with one of our IPs. ...
5
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4answers
3k views

How to send 100,000 emails weekly and avoid being considered spammer

I have a mailing list with 100,000 email addresses, and I have to send it an email weekly. What application/program/webapp/script/etc do I have to use to send 100,000 emails weekly and avoid being ...
5
votes
3answers
673 views

97% of emails reaching IronPort/Domino are Spam

We have a Domino mail server protected by Iron Port (v7.1.5 I think). Iron Port reports an average 96%-97% of emails are stopped by reputation filtering, and around 3% of emails are clean messages. ...
5
votes
7answers
5k views

phpBB: How to handle spammy registrations?

I'm managing a phpBB-based forum that gets hit hard by spammers signing up fake accounts. To combat this, we enabled "administrator activation required", but it's not working so well: When a new user ...
5
votes
3answers
10k views

Sendmail: Sender address rejected (Domain not found)

I'm running into problems with sending mail on our webserver. Some mails are sent and delivered without any problems (eg Gmail), while others are deferred with "Sender address rejected: Domain not ...
5
votes
6answers
9k 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 ...
5
votes
1answer
3k views

How do I do an exact whois search?

When I execute the following whois command on my Ubuntu server, I get all sorts of other domains which contain google.com in the name, but clearly aren't owned by google. As this appears to be some ...
5
votes
2answers
924 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 ...
5
votes
2answers
279 views

Can a Barracuda Spam Filter 300 reject mail based on DNS?

Can a Barracuda SF 300 reject mail based on DNS? Specifically can it respond with a 4XX code for mail claiming to be from a domain without a valid MX or A record (similar to postfix's ...
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
7answers
736 views

Any antispam software beside SpamAssassin?

What other antispam software (server side) is available besides SpamAssassin?
5
votes
1answer
1k views

Stop Outgoing Spam Already Tagged as Spam

I run a Postfix server with Amavis and Spamassassin among other things. Postfix receives mail from the outside world and passes it on to Amavis. Amavis has Spamassassin rate the mail, and then tags it ...
5
votes
2answers
320 views

Attack from anonymous proxy

We got attacked by some very-bored teenagers registering in our forums and posting very explicit material using anonymous proxy websites, like http://proxify.com/ Is there a way to check the ...
5
votes
1answer
831 views

Disable Outlook Web Access Junk filtering in Exchange 2013

By default, Outlook Web Access (OWA) in Exchange 2013 seems to move suspected junk mail to the Junk Email folder. This is undesirable behavior in most of my environments because we have Barracuda Spam ...
5
votes
0answers
2k views

How can I test if my apache server is an open proxy?

Is there a curl command that will validate if a server is acting as an open proxy? I've tried curl --proxy http://<my server>:80 http://yahoo.com But the response from apache is: ...
4
votes
6answers
2k views

Are SPF needed for domains that do not send mails and do not have MX record?

I have some domains registered that do not send mails. I have totally removed MX record for these domains on my DNS. Is it still useful to set an SPF record in order to avoid spammer to send mails ...
4
votes
3answers
620 views

With regard to anti-spam practices, what exactly does a typical reverse DNS check look for?

My understanding is that a typical reverse DNS lookup will compare the SMTP hostname (provided in the EHLO/HELO command) of an incoming connection and verify that it matches the PTR record for the ...
4
votes
6answers
4k 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 ...
4
votes
1answer
227 views

Can a backup mx server be configured to reject email submissions if it can connect to the primary mx?

I know that one technique spammers may use is to send spam to a secondary mail server, since those servers tend to be less powerful and may not have all the spam filtering that the primary has. Can I ...
4
votes
5answers
17k views

How do I get my server off the ivmSIP/24 blacklist?

I checked my server IP using this tool: http://www.mxtoolbox.com/SuperTool.aspx It's come up on the ivmSIP/24 list. What can I do to get my IP removed from this list? I have SPF records set to ...
4
votes
2answers
3k views

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. ...
4
votes
2answers
97 views

Spam addressed to a sender but received by everyone else

Spam's been getting through Postini lately that's addressed to a recipient (bob@example.com) in the To: field and in the headers. While this isn't that strange -- we've had spam get through before -- ...
4
votes
1answer
2k views

Hotmail and Gmail mark emails as spam [duplicate]

Possible Duplicate: How to send emails and avoid them being classified as spam I have been developing a PHP application and one of the features in that application is the ability to send ...
4
votes
3answers
471 views

With valid SPF my mail header becomes huge -> high spamassasin score

I have a dedicated server with a survey system running on a subdomain. The parent domain is hosted on another server. I send email via google apps. Reverse DNS is correct. Without SPF og DKIM, the ...
4
votes
5answers
3k views

Why are email messages sent from my PHP application being treated as spam?

I have this funny thing. When I send an email out, to yahoo, gmail or hotmail users. If I include a link, it will treat as spam mail. But if i removed the link, it will become "inbox", not spam mail. ...
4
votes
3answers
164 views

Spam received to mystery “users” email group

This morning, our entire company received a spam message sent to users@ourdomain.on.ca, where ourdomain.on.ca is our actual domain. There is a distinguished name that this could correspond to: ...
4
votes
1answer
888 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 ...
4
votes
1answer
780 views

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 ...
4
votes
2answers
16k views

AOL bounces with: AOL will not accept delivery of this message [closed]

AOL started bouncing emails from my mail server with the following error: 521 5.2.1 : AOL will not accept delivery of this message. 554 5.5.0 Remote protocol error On the troubleshooting page AOL ...
4
votes
2answers
276 views

Running a mail forwarding service, what are some steps I should take to prevent my IPs being blacklisted

Background: I'm about to launch a service which offers email forwarding for a large number of domains. Say you want people to be able to contact you using you@somesite.com, all emails sent to that ...
4
votes
3answers
433 views

How to detect form spamming on your web servers?

If you run hundred of web sites on your servers, what it is the most efficient, automated way to detect if bots are using your HTML forms to send spam email, even if your forms have some kind of ...
4
votes
2answers
2k views

Is setting up my own SMTP server to send email a waste of time with regards to deliverability?

I have a dedicated host serving a few domains I manage. I host my own email and IMAP server. The server is at buildoneforme.com with IP address 144.76.81.247. I think reverse DNS is working: $ host ...
4
votes
1answer
4k views

IMAP standard folder names - “Junk” or “Spam”

I am configuring spamassassin at the moment and have been wondering what is the standard (or atleast most used and recognized by most clients) folder name for Spam or Junk? I first used Spam, but ...