All Questions
343
questions
0
votes
0
answers
21
views
Should smtp_helo_name always be the same as your MX record?
I can't seem to satisfy HELO checks on SPF records in all cases. I have an SPF record for my domain like this:
"v=spf1 mx -all"
The MX records in the zone are:
mx0.mydomain.org.uk. ...
- 507
0
votes
0
answers
7
views
Why does the SpamAssassin not insert some headers?
Trying to configure SpamAssassin 4.0.0 with Postfix 3.7.10 on Debian 12. I'm using spamass-milter 0.4.0. My /etc/spamassasin/local.cf has the following entries:
required_score 5.1
...
- 1
0
votes
0
answers
37
views
Configure fail2ban to parse multiple log lines, e.g. Postfix mail rejects
I want to to block local authenticated mail users who generate spam, i.e. disable their SMTP access for a while as one of several countermeasures against hijacked accounts and malware.
To accomplish ...
- 149
2
votes
0
answers
65
views
how to protect postfix mail from gmail spam [duplicate]
I am experiencing an issue with the BDIX (Local Bangladeshi server) server.
I have set up a mail server on the local BDIX server using postfix with aapanel.
I have configured SPF, DKIM, and DMARC in ...
1
vote
0
answers
23
views
Postfix configuration to block spammer domain isn't working
I have an Ubuntu 22.04 cloud VM with Postfix 3.6.4-1ubuntu1.3 installed that I largely use for receiving e-mails sent to addresses at my personal domain that I provide when signing up for less-...
- 117
0
votes
0
answers
24
views
SPAM and SPOOF emails from postfix mailserver
I created and configured a postfix server, basically its an smtp-only server. I added the domain i want to use in postfix main.cf, and also added other domains in virtual file. I installed configured ...
0
votes
1
answer
80
views
postfix bounce_queue_lifetime and maximal_queue_lifetime
i have done a lot of research but still cannot clearly understand what is the difference between postfix bounce_queue_lifetime and maximal_queue_lifetime in main.cf. Although I've read a lot of ...
- 1
0
votes
2
answers
163
views
How to detect non-latin scripts in email subject?
On my mail server running Postfix, I want to reject mails using some non-latin scripts in their subject, in particular Arabic and Cyrillic since none of my users (family) speak languages that use them....
- 266
0
votes
1
answer
99
views
postfix sending only short messages ( emails ) but not long messages?
when I am sending a short email from "[email protected]" or any other email acc , the message is received well in the inbox of Gmail , hotmail etc , but if I send the message again with long ...
- 209
0
votes
2
answers
201
views
Spammers are using my mail server to send out emails
Lately spammers are using my mail server to send emails to different addresses.
For example, a colleague of mine received an email that was supposedly self-sent (it was not).
Looking at the ...
- 1
0
votes
0
answers
24
views
Server still sending spam despite closing relay with postfix [duplicate]
I have an Ubuntu 20.04.5 LTS with multiple Wordpress website running on Nginx.
I installed postfix and configured it to stop relaying emails.
I have an antivirus freshclam running.
Someone or ...
- 101
0
votes
0
answers
204
views
In Postfix, how do I block all clients whose reverse DNS is in a domain?
I just got hit by a spammer sending spam through my mail server from multiple IP addresses in various netblocks all with a reverse lookup ending in googleusercontent.com. (I haven't figured out how; ...
- 101
2
votes
1
answer
216
views
"Non-Open-Mail Relay" Postfix / Dovecot are relaying anyway; Mis-configured or CRACKED? Plus, presently blocked external users need access too
CRITICAL UPDATE
While working on this, there'd been no spam relayed for over a single day so I left it up and overnight, TWO emails got relayed! ACK!
Here they are, from my tail / grep commands (...
- 1,298
-1
votes
1
answer
37
views
Long established Postfix / Dovecot environ had to be rebuilt, became an open relay; How do I know fore sure it's fixed, and, if not, fix it fast?
Because it's bad form here to ask multiple questions in ONE entry, I'll be asking about specific Postfix and Dovecot entries, however this nightmare has been going on since about January 19 and it's ...
- 1,298
0
votes
1
answer
628
views
Completely block any outgoing emails
I have a server with Postfix, running in Docker. The server is supposed to only receive emails, not send them.
I added the following iptables rules to try to block anything getting out from port 25:
...
- 103
1
vote
1
answer
3k
views
Spamhaus is blocking several customers since a couple of days?
I received a couple of complaints from customers that got their emails rejected.
I haven't changed my config, so this must be an issue with spamhaus.
I'm running Postfix with these settings for ...
- 353
0
votes
1
answer
162
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 ...
- 155
0
votes
2
answers
2k
views
How to prevent unauthorized relay of mail in Postfix
It seems that our mail server is being used to send spam.
The sender of the email is a spoofed real account on our server.
There is no email in the sent history for that account.
I would like to ...
- 3
4
votes
1
answer
2k
views
Reject emails that fail reverse hostname resolution
My Postfix server is receiving spam from an ever changing set of domain names but with a consistent pattern in the log file starting with line warning: hostname X does not resolve to address Y. No ...
- 155
1
vote
1
answer
690
views
Can't Receive Email - Postfix iRedMail Server Using Spamhaus & Unbound / BIND9 DNS Servers
iRedMail server configured using ISP's DNS servers. Running several years without issue. Moving from current ISP to Starlink. It appears Starlink uses Cloudflare's public DNS. Currently have both ISPs ...
- 11
1
vote
2
answers
283
views
How to block spoofed mail from *.host.com
I'm currently running a centOS server with directadmin and custombuild.
I keep getting spoofed phishing mails with spoofed from addresses that have SPF setup properly.
Spamassassin gives it a score 1....
- 131
2
votes
1
answer
196
views
Privacy-friendly Postfix bounce messages for remote rejects
The topic of handling bounce message for remote rejects has been brought up at least three times (1, 2, 3), and it looks as if there is no real solution. I wonder, though, if the bounce template can ...
- 267
0
votes
0
answers
268
views
Postfix Maildrop Directory Generating Unsolicited Email
I have recently set up up a Postfix Mail Server on Ubuntu 20.04. This server is used mainly to relay messages from authenticated users to the outside world. This is so applications such as payroll ...
1
vote
1
answer
76
views
Outbound email restriction
We have a project to set up around 5,000 plus email IDs for an educational institution. Emails are meant mostly for receiving mails, and the instituition wants to set up some rule that no email id can ...
- 685
0
votes
1
answer
440
views
Postfix identify the true sender
Recently my server has many spam emails generated. I looked for information in an example message but the sender is apparently faked, and there is no postfix user ID in the message header as well. ...
- 15
0
votes
1
answer
394
views
Postfix: Optimising order of spam checks?
I have a mail server (postfix v3.3) on a VPS running Ubuntu 18.04, processing both inbound and outbound mail (I have some websites sending mail, and some SASL auth users with accounts on the machine) ...
- 507
0
votes
2
answers
495
views
Configure Postfix external relay for UCEPROTECTL3 rejection
Is it possible to configure MTA Postfix server to bypass UCEPROTECTL3 rejection ?
Example when my server connect to recipient server then I get information:
Diagnostic-Code: smtp; 554 5.7.1 You are ...
- 51
0
votes
1
answer
592
views
What to do if a specific postfix/dovecot user's account is hacked and being used to send spam?
I'm running a postfix/dovecot mail server. This morning, I discovered it was unresponsive. Turned out, /var/log was full. It appears one of the users has had their account hacked and it's being used ...
- 419
0
votes
0
answers
380
views
DKIM validation fails only on Outlook
I'm configuring OpenDKIM to sign miltiple domains with the same key on Pstfix. I followed this tutorial with s=mail and d=example.com.
SigningTable:
* mail._domainkey.example.com
KeyTable:
...
- 11
-1
votes
1
answer
446
views
Is it possible to scan local drive folder for SPAM Mails? [closed]
I want to check a postfix mailbox folder directly on the Server. The server OS is Debian.
Is this possible?
- 101
0
votes
0
answers
212
views
Discard an email in postfix when the reply-to address is different from that of sender
I've setup virtualmin and the emails are working fine with the Postfix server. However I'd like to add a feature where, in case somebody tries to abuse the server and tries to send an email with a ...
- 1
1
vote
1
answer
1k
views
How to analyze cause of postfix server sending spam
A client of mine has a server hosting postfix as well as nginx with several websites, including an nginx installation with several subdomains / websites.
Since a couple of days the /var/spool/postfix ...
- 125
0
votes
0
answers
18
views
My postfix is used for spamming [duplicate]
I need your help.
My postfix is sending spam mails.
I checked my main.cf and it should be fine.
In the following a snippet of my mail.log
Jan 3 22:35:41 mail postfix/pickup[104179]: 866352963F01: uid=...
- 1
0
votes
1
answer
778
views
Postfix: How to malware & spam scan outgoing SMTP SASL auth users?
Although I have found two answers to this, I can't work out how to actually implement them, and at least one of them doesn't actually answer the question. So if anyone has any experience to share I'd ...
- 507
2
votes
2
answers
3k
views
Postfix - How to enable SMTP authentication on local delivery
I have an email server running Postfix. Everything is working fine,
However, recently, some internal emails received emails from their own addresses with phishing content.
After finding out, I learned ...
1
vote
0
answers
239
views
Spamassassin keeps marking as spam despite low score
I have postfix with Spamassassin and spamass-milter configured.
E-mails with score higher than 4.0 are supposed to be treated as a spam and be rejected.
Here is my local.conf
rewrite_header Subject ***...
- 11
1
vote
2
answers
906
views
Postfix does not retry after 451 error / greylisting
I have a forwarding server using postfix/dovecot that receives emails from a third party mail client (say gmail) and forwards the emails to the final recipient.
I have noticed that when the recipient ...
- 169
0
votes
1
answer
737
views
Provider for outgoing mail from own Postfix server
I've been running Postfix on my own dedicated server (hosted by Hetzner) for years, however, it's getting increasingly difficult get outgoing mail to Outlook/Hotmail and sometimes Google delivered. ...
- 145
0
votes
1
answer
472
views
How to address spam bounce on exceeded quota issue?
I'm investigating a mail server blacklist issue.
Our mail server had a user over quota, which resulted in emails being bounced back to senders with a"user over quota" message. Some of these ...
- 645
0
votes
1
answer
318
views
Postfix seems to ignore spam miltering for LMTP
I use SpamAssassin through a milter to check e-mail, but it seems postfix does not check local delivery (like contact forms). How can I force Postfix to treat all mail as 'foreign'?
- 105
-1
votes
1
answer
434
views
Ubuntu 16.04 Postfix works, but email goes to SPAM
Hello i follow this guide to install Postfix
https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-postfix-as-a-send-only-smtp-server-on-ubuntu-18-04
and i added SPF, dmarc ...
- 3
0
votes
1
answer
190
views
Why are my Postfix mails recognized as Spam? [duplicate]
I have a Postfix mail that I have configured pretty good. mail-tester.com gives me a 10/10.
I have tested on both Google and Yahoo, and checked their headers. Nothing seems to be wrong in the headers.
...
1
vote
2
answers
455
views
Our IP was listed by Spamhaus - how can we prevent this from happening again?
I'm the technical assistant at a small-town public library where we run our own e-mail. If it matters, it's Postfix on an Ubuntu 18.04 box. Gateway / firewall is a 16.04 box with port forwarding set ...
- 171
5
votes
2
answers
15k
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 ...
- 359
0
votes
1
answer
1k
views
postfix server on VM - mail relay
I've setup a mail server according to this setup: https://thomas-leister.de/en/mailserver-debian-stretch/
The documentation itself looks quite good to me - is well explained and seems to work... ...
- 111
1
vote
1
answer
1k
views
how to reject emails with specific subject on Mail server postfix spamassassin?
I have postfix and spamassassin. recently I found an email with subject "XXX" to all company email addresses and aliases.
So I was wondering if I can reject sending emails with specific subject "XXX" ...
- 21
0
votes
0
answers
154
views
Postfix forward mails to external domains as (inline) bounce
My problem: I own a postfix server with several Aliases on it. For example:
[email protected] => [email protected]
If I now send a email from [email protected] to [email protected] it get's forwarded to [email protected]
...
- 101
0
votes
1
answer
112
views
Drop newsletter emails with Postfix
There is an option, i have seen in Fortimail, that makes you able to filter/drop all newsletter emails.
I don't understand how Fortimail detects these type of emails.
And I am keen to know whether ...
- 773
0
votes
1
answer
1k
views
How to cut-off spam (postfix+amavis-new)
I'm using postfix+dovecot+amavis-new+clamav+spamassassin+postgrey on my Ubuntu based VPS.
Since some days i'm receiving a lot of spam, with a low level of spam score in headers.
Common for all spam ...
- 1
6
votes
2
answers
1k
views
Postfix: ACCEPT if RBL and SPF checks pass, DUNNO/greylist otherwise. How to do it?
I would like to accept all clients that pass RBL and SPF checks (and possibly some checks, but these are minimum requirements for me), and greylist those who don't. When a client passes the SPF check (...
- 61