Linked Questions

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 ...
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
1
vote
4answers
2k views

Prevent spamming [duplicate]

How to prevent spamming in Cpanel / Linux server ?
2
votes
3answers
2k views

Should I reject email on SPF and/or DKIM failures? [duplicate]

I’m administering a mail server (cPanel/WHM) running Exim. It handles normally a few hundreds incoming emails per day for our customers. I’m not sure if I should reject SPF and/or DKIM failures for ...
-1
votes
1answer
1k views

Suddenly Gmail and Hotmail block our emails [duplicate]

Starting from yesterday, all emails sent from our server are being rejected by Gmail and Hotmail. Everything was working properly until now. Here are the error messages received: Gmail Failed ...
-1
votes
1answer
789 views

sendmail - Server Sending Spam? [duplicate]

for the past day my server is being used to send a spam. I'm using the Amazon Linux Distro (RedHat based). It has sendmail 8.14.4. It is setup to require authentication, SSL etc. Below are some ...
0
votes
2answers
293 views

DKIM, spam probability, signing with key at mail server vs sender domain? [duplicate]

I'm working on an email marketing tool and so far we've been recommending our customers to set up an SPF-record (Sender-ID) and a DKIM-record, we also have our own SPF-record on the mail server and a ...
0
votes
4answers
572 views

Stopping incoming spam with sendmail [duplicate]

I am having an issue due to a "smart" sysadmin that made some choices while I was away for two months: Spam. I manage probably close to 10,000 web/mail sites. He decided to allow all mail to ...
0
votes
1answer
156 views

Project Honeypot says my mail server has become a spammer [duplicate]

I need help diagnosing this: http://www.projecthoneypot.org/ip_66.18.204.186 It says my server has been sending spam for 4 months! I try to be a responsible mail server admin, I hate spam, I do ...
0
votes
1answer
105 views

Prevent Email Going to Spam [duplicate]

I've set up my own server and I'm really struggling to stop any outgoing email go to spam. I've used allaboutspam and mail-tester.com to test it and they both come back with perfect results. No ...
0
votes
1answer
55 views

Blocking spam with SpamAssassin [duplicate]

I have a server that runs websites and exim for e-mail. I've added countless RBLs including barracuda to try and cut back on incoming spam. However, they still keep coming in. The clients use ...
0
votes
1answer
51 views

I guess that my mail server is unprotected and spammers are using my mail server to spam myself [duplicate]

Since I switch to my own mail server (I folowed this two tutorials: https://www.linode.com/docs/email/postfix/email-with-postfix-dovecot-and-mysql and ...
0
votes
1answer
62 views

can someone explain this exim mainlog lines? [duplicate]

i dont understand this lines in exim mainlog , may anybody explain this ? my server is sending spam and i need to stop it. 2015-04-25 07:51:42 1Ylqf0-0000TF-G1 DKIM: d=mandrillapp.com s=mandrill ...
-4
votes
1answer
43 views

No way to create an effective spam filter [duplicate]

We are having a big spam problem and we don't know how to resolve it. We have one spammer that send us mail daily. All these emails are from different themes, using different email addresses that are ...
0
votes
0answers
13 views

EXIM alloying in spme despite strict rules [duplicate]

Here is a copy of a header from a recent spam e-mail: Return-path: <Deals---Alert@headja.cricket> Envelope-to: user@domain.tld Delivery-date: Tue, 07 Apr 2015 22:58:51 +0400 Received: from ...
0
votes
0answers
11 views

getting lots of spam from “unknown” and helo localhost [duplicate]

On our server, we keep receiving spam with the following headers. We are using whm 11.44 and exim. Return path is always: Return-path: <> and it says Received: from unknown (HELO localhost) Both ...
43
votes
6answers
73k 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 ...
22
votes
2answers
5k views

What are SPF records, and how do I configure them?

This is a canonical question about setting up SPF records. I have an office with many computers that share a single external ip (I'm unsure if the address is static or dynamic). Each computer ...
18
votes
5answers
535 views

Is it good practice or too draconian to reject mails from mailservers with no RDNS

I've recently dropped SpamAssassin and am now basing spam rejection on DNSRBL's, grey-listing and other basic tests and I'm wondering whether I should also block hosts that don't have a valid RDNS ...
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 ...
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 ...
7
votes
5answers
5k views

Is there any alternative to SpamAssassin? [closed]

I'm looking for an alternative to Spamassassin. Anyone tried rspamd ?
5
votes
6answers
1k views

Prevent outgoing spam

What are some ways to prevent spam from leaving your servers should a hosting account get compromised? Have a bunch of clients on a server with cpanel but wondering if there was a way to just ...
5
votes
2answers
5k views

In postfix, how to enforce tls + auth over 587 while leaving tls optional for 25

I would like to host mail services for some domains. I have succesfully setup postfix to consult sql for those virtual domains. What I would like to do is: For connections on 25: 1. Deny relaying ...
1
vote
2answers
1k views

Spam mail through SMTP and user spoofing [closed]

I have noticed that it's possible to telnet into a mailserver that I own and send spoofed messages to other clients. This only works for the domain that the mail server is regarding; I cannot do it ...
5
votes
1answer
566 views

Does postfix reject spoofed senders?

Is there a reliable way to reject incoming mails with a spoofed e-mail address? What kind of checks does postfix run normally on incoming mails? does postfix check the reverse dns by default? does ...
2
votes
2answers
583 views

DNS and SPF configuration for Microsoft Exchange

We've started receiving spam with spoofed addresses from our own domain. So I'm trying to get my PTR and SPF records etc correct to prevent it. We're running Exchange 2010 on site with one server ...

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