Questions tagged [spam-filter]

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Mail signature invalid because of encoding of dots in quoted-printable mail

This is a repost so i will link the post: https://security.stackexchange.com/q/274208/227343 I‘m sending a mail encoded with quoted printable encoding that contains some dots „.“. There is a problem ...
1 vote
2 answers
2k views

Postfix's header checks not working as expected

This question continues from this identical but focuses on another aspect of detail: the Postfix testing tool and the different options. As the OP of the linked question, to prevent spam, and ...
0 votes
1 answer
94 views

Different spam filter method for sasl-auth clients?

Using a standard Ubuntu postfix setup (Ubuntu 22.04), I would like to filter mail as follows: Incoming submission and smtps (the vast majority of mail): SPF and RBL checks (I'm using policyd.pl), ...
-2 votes
1 answer
59 views

Spam filters: IP address with no history v. good history [closed]

Zoho gave me an IP address with no history this week. Senderscore.org says there's insufficient data to evaluate it. At other times Zoho has assigned me an email sending IP with a fair or good score. ...
0 votes
1 answer
57 views

Spamassassin How to stop domain email containing only numbers?

There are more and more spams coming from domain containing only number like 23821.com. You can see an example in the message header below. Received: from hmdablm ([116.186.123.166]) by 23821.com with ...
0 votes
1 answer
112 views

Sign-Up verification emails going to spam despite proper authentication

I am using SendGrid to relay emails sent via Drupal. I am struggling with Gmail specifically marking Sign-Up verification emails as spam despite using DKIM, DMARC, SPF, reverse DNS, everything there ...
0 votes
3 answers
2k views

Any way to bypass Barracuda spam filter for specific addresses?

We are a medium-sized company planning to switch our spam filter service. Right now, our computing solution provider hosts a Barracuda service on its server. Our emails are routed there and filtered ...
0 votes
0 answers
72 views

Multi-message anti-SPAM filter in SpamAssassin

My vendor's database has been stolen and I started to receive spam messages in a huge amount. It is being sent by spambots / spam scripts, so sender and recipient email addresses are always fake. The ...
0 votes
1 answer
574 views

Spamassassin not scoring correctly

I have Spamassassin running on a Ubuntu/Plesk server. It was working relatively well until recently but now seems to be letting through random spam messages. These messages seem to trigger plenty of ...
4 votes
2 answers
14k views

Spam passing postfix config "hostname does not resolve to address: No address associated with hostname"

On a postfix MTA MX setup, I have a spam mail pass two checks which it definitely shouldn't. The postfix/smtpd process logs these warnings, which should be a hard fail in this setup: hostname * does ...
1 vote
0 answers
131 views

Include matching rspamd rules in mail headers

Spamassassin has a feature to include the matching rules in the headers of mails flagged as spam, so one can see why the mail was classified as spam and possibly adjust or create mailbox filters that ...
0 votes
2 answers
101 views

Is an email server that accepts an email and then silently filters it out complying with SMTP standards?

Can you send an email to an address, have it be accepted by the mail server, and then the mail server silently deletes it? I am running an email server. I have noticed that some emails come from IP ...
1 vote
1 answer
320 views

How to whitelist our own outgoing emails from being blocked in amavis/spamassassin using Spamhaus' block lists?

Just after we implemented spam filtering on our Postfix server using spamassassin-dqs through amavisd-new we drastically reduced received spam, but to our surprise our own outgoing e-mails are being ...
3 votes
1 answer
2k views

Exchange 2013 IPBlockListProvider blocking some (but not all) matched IPs

I have configured our Exchange 2013 Edge Transport server to utilize several IPBlockListProviders including Spamhaus. While they work great most of the time, there are still some emails which despite ...
0 votes
1 answer
3k views

Postfix allow incoming mail for specified domain from specified ips

I am running a Postfix mail server. Some domains are configured that the DNS MX record is set to an antispam service. This service is forwarding the good mails to our mailserver. Some sender are ...
1 vote
0 answers
348 views

Email Sieve to Target emails with a specific pattern in a catchall domain address

I have the following email formats: [email protected] [email protected] [email protected] [email protected] I create them on the fly when I sign up to different sites. I'm having an ...
2 votes
1 answer
4k views

DMARC record is valid, but your domain's None/Quarantine policy does not yet protect it against email spoofing and phishing

People, Using the website: https://easydmarc.com/tools/dmarc-lookup?domain=name.com I got this error: DMARC record is valid, but your domain's None/Quarantine policy does not yet protect it against ...
0 votes
1 answer
153 views

Postfix - Eliminate sender domain based on recipient email address

Does anyone know of a way, using Postfix, to block a domain as soon as it tries to send to a specific recipient address? Spam typically goes to several recipients in my organization. Some email ...
0 votes
2 answers
5k views

Exchange 2013 - Remove warning text from outgoing email body

I created a transport-rule in our Exchange server 2013 where it will add a warning text on top of email-body to all external incoming emails. This is to alert employees about potential risks in ...
0 votes
1 answer
130 views

Antispam Exchange Online Permission Error

We have Office 365 Accounts and also an Microsoft hostet Exchange online Server. Normaly i could manage my antispam Rules and Policys in the Exchange Admin Center. A few months ago there was the new ...
2 votes
2 answers
788 views

body_checks: How to filter base64 encoded content?

The idiomatic answer is probably "don't - use a filter that decodes the message first", but as can be seen in the second answer to that question, it should also be possible with body_checks ...
6 votes
4 answers
4k views

What is DNS TXT record "mailru-verification"?

Sometimes I see this mailru-verification DNS record. I've Googled - and Yandexed ;) - but I found nothing about it. I suspected that is a kind of russian SPF implementation... dig example.com TXT ...
1 vote
1 answer
447 views

Postfix no longer rejecting emails based on spam block lists

My postfix server is configured to reject emails based on a couple of spam block lists administered by spamhaus and spamcop. After noticing that I've been receiving more spam than normal recently, I'...
1 vote
0 answers
106 views

spamassasin unable to read Japanese when it is html encoded

I would like to block some emails which contains certain Japanese words, but spamassassin fails to detect such words when the email is HTML encoded, for example: This is a multi-part message in MIME ...
1 vote
1 answer
3k views

How to block SendGrid spam with sendmail?

Sendgrid and MailChimp are the two biggest sources of spam captured in my spam-folder. I'd like to block them before they get there. Fortunately, in an effort to appear "legitimate" the spammers ...
8 votes
2 answers
13k 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 ...
1 vote
0 answers
146 views

Continuous SPAM from certain IP/s hosting provider, how to report them if not responding at [email protected]

last maybe 4 weeks is coming SPAM e-mails from various domains. In common is that when i paste the source code of the e-mail to https://www.spamcop.net is detected this provider and their mailbox: ...
1 vote
1 answer
293 views

How to minimize chances of one's domain being falsely blacklisted (uribl)

My side job is to admin my wife's company domain. It's only used as a domain name for Google mail and tools (slides, docs, etc...). Although she used her domain for email for many years without any ...
0 votes
0 answers
200 views

eMails sent from G-Suite go to Spam in Gmail clients. IP and Domain not blacklisted

We are running a platform with + 1 Mio users who sign-up with double opt-in to nurture them and allow them to be notified etc. All notifications by email are using our main domain (example.com) that ...
1 vote
3 answers
4k views

Exchange 2010 ignoring SPF record

we are using Exchange 2010 and have already setup SPF record for our authorized mail server IPs. As a test using our domain name i tried to send an e-mail from another computer on the internet which ...
0 votes
1 answer
67 views

Is it ok (regarding spam) to use yahoo to send email from our domain [email protected]?

I m enough of seeing my email arriving in spam folder. I would like now to send my emails not from my smtp server but from yahoo mail server. When you have a yahoo account, you can choose to send ...
0 votes
0 answers
666 views

Enabling X-Spam-Report in SpamAssassin

I tried to enable header X-Spam-Report in local.cf: report_safe 0 Per instructions this should cause adding this header to emails. Yet the header is not there. How can I fix that?
1 vote
0 answers
306 views

Kolab 3 outbound mails spam detection

I installed Kolab on a local server and I need a way to allow it to reject spam mails before they are sent. One method that I found is to install postfix and spamassassin in another server and ...
-1 votes
1 answer
62 views

How is it possible for spammers to keep pestering me with FAKE domains when all e-mail sending providers have these insane obstacles to go through?

I keep getting e-mails to my Gmail account from made-up domains such as: @mtixusu9shbyusyr6.org.uk @mpqyriexqpvramtkn.org.uk And so on... (Yes, I checked some of them and they are not actually ...
0 votes
1 answer
638 views

Can I disable spam filtering for one user in Exchange Online Protecttion?

We are using Exchange Online Protection in front of our on-premises mailserver. Is it possible to disable the spam filtering for one user only?
98 votes
8 answers
196k 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 ...
-1 votes
1 answer
192 views

Mail Server IP address is getting blocked by Spamhause

I have use my mail server public IP address for years. But now it is blocked by spamhause. But no special no illegal activities happened on my network. We have very good monitoring solutions and no ...
0 votes
1 answer
37 views

Exchange/ePrism quarantine settings

I'm temporarily overseeing the company's infrastructure while we find a replacement for someone who recently left. We have on-premise exchange with ePrism (EdgeWave). Most of our users find our email ...
3 votes
0 answers
2k views

Accept or not to accept DKIM signed emails on my smtp server which source DNS don't has signature [closed]

In the outgoing emails we use in our domains SPF + DKIM without any problem. But with the inbound emails some time ago we're receiving emails from some of our customers/suppliers signed with DKIM, ...
10 votes
2 answers
9k views

Recommended way to implement Postfix 'before-queue' SpamAssassin filtering?

After some discussions with colleagues and the relevant depts. in my office, I have come to the conclusion that for my Postfix server, I must implement a before-queue filtering. The reason is that ...
1 vote
1 answer
6k views

Exchange office 365 transport rules to block spam when FROM doesn't match smtp.mailfrom or return path

I'm sure this type of question has been answered already so I apologize in advance, but I can't seem to find anything. I have spf, dkim, dmarc all setup so I'm not worried about outgoing spam, but I ...
0 votes
1 answer
49 views

why two spam policy apply on the same email

Recently, we made some Spam setting as below shown, but don't know why the result is, emails are prepended with 'spam' and move to junk mailbox at the same time. We want SCL 5 emails is prepended with ...
1 vote
1 answer
759 views

Gmail detects emails as spam from domain with neutral reputation

I have a new domain and mail-in-a-box server set up correctly. Unfortunately, when sending to Gmail, it treats emails from my domain a a spam. The domain is not blacklisted and DNS settings are also ...
2 votes
0 answers
1k views

Rejecting emails with mismatched Header/Envelop FROM

We've been receiving some spam/phishing emails that are managing to get through on occasion and the majority have a MAIL fROM our domain but their ENVELOPE from is whatever spammy address. My ...
0 votes
2 answers
3k views

SPF issue with different HELO FQDN

I am trying to setup SPF/DKIM/DMARC on my email server on a VPS. Here is my DNS configuration (DKIM & DMARC removed for readability) : @ 28800 A X.X.X.X @ ...
2 votes
1 answer
759 views

Postfix reverse MX check

Is there any way to configure reverse MX check for Postfix to check incoming emails? I just noticed that most of our spam which are still coming true are sent (or seems to be sent) from properly ...
1 vote
1 answer
755 views

Postfix - Send spam to different email address

I've researched for an answer to this question and can't find anything. I have Postfix running on Debian Stretch. I will soon be setting up Rspamd. Here's the logic of what I want to have happen ...
0 votes
1 answer
41 views

Incoming Email Server (I think) is Blocking Email Form

I’m not a server professional of IT person, so ignorance is admitted in terms of configuring servers. But this is why I am seeking direction from someone who knows more. When I build websites, it is ...
0 votes
1 answer
1k views

filtering spam emails with Chinese subject

A client have ton of Chinese spam. All look similar to this one: Return-Path: <[email protected]> X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on hotel492.dedicatedpanel.com X-...
0 votes
1 answer
1k views

How do I get Courier Maildrop to log data?

Background I'm running Ubuntu 16.04 LTS on a virtual machine. It is the mail server for a small medical clinic. We are trying to move mail filtering from the client-side to the server-side, and I am ...