Linked Questions

68
votes
9answers
32k 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
628 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
248 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
488 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
127 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
73 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 ...
-4
votes
1answer
41 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
1answer
30 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
26 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 ...
-1
votes
0answers
22 views

new domain extensions are going into spam filters, anything we can do? [duplicate]

We got one of those new domain extensions (.xyz) and alot of people that we send mails to are saying that our mails goes into their spam folders. Are there anything we as a company can do about that ...
0
votes
0answers
10 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 ...
37
votes
4answers
4k 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 ...
17
votes
5answers
463 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 ...
17
votes
2answers
3k 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 ...
6
votes
4answers
997 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 ...
20
votes
3answers
1k 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
5answers
5k views

Is there any alternative to SpamAssassin? [closed]

I'm looking for alternative to spamassassin. Anyone tried rspamd from Rambler.ru (https://bitbucket.org/vstakhov/rspamd/wiki/Home)?
4
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 ...
2
votes
2answers
3k 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
902 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 ...
2
votes
1answer
2k views

Cloudflare, reverse DNS and php mail ending up in spam folder

I've been using Cloudflare to host my DNS, and PHPMailer to send e-mail through ZOHOs SMTP servers with great success, but have found that all my e-mails are hitting Gmail, Zoho and Hotmails spam ...
0
votes
3answers
2k views

smtpd_helo_restrictions = …, reject_unknown_helo_hostname occasionally rejects mail I care about, how to handle?

I have configured my postfix as follows: smtpd_helo_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unknown_helo_hostname This is working well because most spambots don't seem ...
4
votes
1answer
171 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 ...
-1
votes
1answer
423 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 ...
0
votes
2answers
2k views

Receiving spam where sender is @mydomain [duplicate]

Possible Duplicate: How to stop people from using my domain to send spam? I am running a mail server with Ubuntu + Postfix + Maia Mailguard + Dovecot, all has been working well until ...
-1
votes
2answers
850 views

Postfix is Sending Spam [duplicate]

I have an Ubuntu 12.04 server, hosted on AWS, that powers a dozen WordPress installations using Nginx and php5-fpm. The problem just began one day. My server was down. Panic! Whenever I turned it on ...
1
vote
2answers
582 views

Postfix - unable to access externally

So I can't seem to access smtp from externally. When using a desktop email client (eM client and thunderbird both fail) I can't get it to hit the server at all. (eM client is trying to hit: ...
-1
votes
1answer
950 views

Configuring postfix to fight spam, 2012 edition [closed]

EDIT: This question was poorly asked, later I found another question which answers what i wanted to know: Spam prevention tips for Postfix I'm running a small (20 users, 30 mailman-lists) server with ...
1
vote
2answers
95 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 ...
5
votes
1answer
272 views

How to use two mail servers in parallel, if possible?

I basically want to have two separate email servers. The first one is the GoogleApps GMail service, which is for humans to use. The second server would be for sending messages from my application (so, ...
-7
votes
2answers
703 views

Mail server not sending or receiving after removal from barracuda blacklist to white list [duplicate]

Possible Duplicate: mail loops back to myself | postfix Mail server not sending or receiving after removal from barracuda blacklist to white list. I've checked against black lists and the ...
0
votes
2answers
232 views

Many invalid HELO from

I've been recieving many invalid helo requests from a Microsoft domain. I already did send a question about this but they still do not respond. maillog: Jan 14 19:27:14 relay postfix/smtpd[57104]: ...
0
votes
1answer
167 views

Postfix forwards to Gmail being rate limited even with unmodified headers

I've installed Postfix on Ubuntu 14.04 with the defaults. I then configured some virtual aliases to forward email from a few addresses to various personal (mostly Gmail) accounts. This is just to make ...
0
votes
1answer
244 views

IIS6 SMTP server retrying too fast (after 451 greylist)

I have my IIS6 SMTP server with default retry settings of 15 min, 30 min, etc. but under some circumstances it keeps retrying every minute (or less). How can I fix this? I have seen it retry ...
0
votes
1answer
173 views

smtp(s) proxy to monitor outgoing spam

I am looking for a smtp proxy to install on our gateway which should monitor outgoing smtp traffic to identify the source of recently occuring spam attacks from our network. It would be enough if ...
-3
votes
1answer
97 views

Inspecting the E-mail traffic of a Windows Server 2008 R2 [closed]

I have seen that the IP address of my mail server has added to blocked IP address list on http://psbl.org. I am using this server for personal use. So, it is not that much of an issue that I am, as a ...
0
votes
1answer
81 views

Steps to make sure network is not blacklisted…Again

I have an interesting issue. I have a client that just got blacklisted due to spam being sent out over the last 2 days. I have my firewall configured to only allow mail to go outbound on port 25 ...
1
vote
2answers
51 views

How to block IP addresses from port 25 [closed]

PROBLEM: Users are getting 15-20 SPAM emails per hour, even with SpamAssassin set to its most aggressive settings SOLUTION: SPAM filtering services are available from companies like McAfee (Intel). ...