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1 vote
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My email server IP is blacklisted, how can I resolve it?

The IP of our email server 154.116.254.147 was added to the UCEPROTECTL2 blacklist. The error message we received is as follows: "I am deeply sorry, but I was not able to deliver your mail to the ...
Sistemas DSRC's user avatar
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 ...
Rumaion Tomal's user avatar
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 ...
Hussein Khazem's user avatar
0 votes
1 answer
104 views

Weird email spam issue. Google Domain Exchange email server

We have a client who is blocking our email domain. Their IT wrote this to us. I've never seen this be an issue before. You are hosted on Google but have entries referring to Microsoft email protection ...
Phi's user avatar
  • 101
0 votes
1 answer
164 views

Amavis outbound mail filter for Postfix?

Running Postfix on Ubuntu 22.04, I'd like to make sure all outgoing mail originating from the server (eg mail forms on websites and stuff) is filtered for spam and malware. I'm using Amavis, which is ...
TommyPeanuts's user avatar
0 votes
1 answer
313 views

How to make a mail server spam "proof"

I work for a German company that sends several thousand emails to our customers every day. Our employees send their emails via Microsoft 356, but the system does not use a mail server and sends emails ...
Pa0x43's user avatar
  • 15
3 votes
2 answers
722 views

Changing hostname for the purpose of email delivery

I have email delivery issues, and MXtoolbox says "Reverse DNS is not a Valid Hostname". I have A and AAAA records for domain.com and mail.domain.com. The data center has set up reverse DNS ...
Mikkel Rev's user avatar
0 votes
0 answers
530 views

Sendgrid IP Address Consistently Blocked on RATS-Spam

Overview For our application, we use SendGrid to send emails to many of our users. Recently over the past few weeks, our SendGrid IP addresses have been added to the RATS-Spam blacklist multiple times....
su-ayoo's user avatar
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: ...
Nifhel's user avatar
  • 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 ...
3und80's user avatar
  • 353
7 votes
2 answers
1k views

How can I create and update the existing SPF record to allow more than 10 entries?

How can I include another SPF record if my existing domain already has 10 lines of SPF records in the TXT record? I wanted to add these two: include:mailgun.org include:sendgrid.net This is my ...
Senior Systems Engineer's user avatar
0 votes
1 answer
816 views

Send email from Heroku server using gmail account and PHPMailer

I have a Heroku app which has a php script that send out an email. The email sent always goes to spam. Let's say the heroku app is mywebsite.herokuapp.com and my email is [email protected]. Based on ...
yem's user avatar
  • 101
1 vote
1 answer
194 views

After adding a new DNSBL to Sendmail, how can I resubmit an email to see if it will be rejected?

TL;DR How can I fool my own sendmail into thinking an email comes from a particular ip address, so that it rejects the message due to a DNSBL match? Details: I run my own mail server, and most spam is ...
PFudd's user avatar
  • 73
3 votes
1 answer
2k views

Why does rspamd consider an odd number of URIs in an email to be an indicator of spam?

Rspamd has many email spam heuristics, and one of them is URI_COUNT_ODD. This heuristic seems to just count how many URIs are in the body of the email, and adds 1 to the score if the number is odd. ...
kuilin's user avatar
  • 139
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 ...
philolegein's user avatar
1 vote
0 answers
294 views

Google Postmaster: IP reputation of subdomain and main domain identical

We have a main domain, example.com. We use this to send regular emails via Google GSuite. We also have a subdomain, say sub1.example.com. We use this to send campaign emails through an email marketing ...
Damnum's user avatar
  • 111
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: ...
Demba's user avatar
  • 11
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 ...
Mathew's user avatar
  • 1
0 votes
1 answer
69 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 ...
zeus's user avatar
  • 133
2 votes
0 answers
1k views

How to solve '521 5.7.1 Service unavailable; client x.x.x.x blocked using Return-Path'?

How to solve or interpret following error? I'm not sure if anything should be done on client (sender or sending account of a domain) or ask remote postmasters for help. <[email protected]> (...
Jiri B's user avatar
  • 597
0 votes
2 answers
237 views

Suspicious Exchange message queues filling up disk space

So i came across my HD space getting full too quickly and after doing some inspecting with wireshark and powershell. It seems my email server is being used as a relay for spam. I closed port 25 on my ...
xR34P3Rx's user avatar
  • 197
1 vote
1 answer
3k views

emails to Yahoo are ending up in SPAM folder despite spf=pass, dkim=pass and dmarc=pass

Are we possibility having a reputation problems with Yahoo emails? Yahoo raw mail header finds my policy I published: dmarc=success(p=REJECT,sp=REJECT) Emails to clients at Google and Outlook are not ...
MeSo2's user avatar
  • 274
0 votes
0 answers
43 views

How do I ensure that only my e-mail server is sending e-mail through my network?

This is a follow-up to Our IP was listed by Spamhaus - how can we prevent this from happening again? - unfortunately, it is happening yet again. I was thinking that people could have malware on their ...
Will Matheson's user avatar
1 vote
0 answers
546 views

Yahoo Mail server constantly deferring mail from my server "due to user complaints"

I have a 100% no-spam score on mail tester. Have no problem with Gmail server, all users getting my emails. Have everything like SPF and other spam related criteria enabled. Yet, Yahoo mail server ...
thenondeveloper's user avatar
1 vote
0 answers
356 views

The DMARC test failed but we didn't find any obvious reason why

One of our users recently found out his emails are going to spam for some reason. This made me dive into everything and the last thing I can't seem to figure out is the Dmarc. We're using gmail for ...
Edan Ben-Atar's user avatar
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. ...
C. Keylan's user avatar
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 ...
Will Matheson's user avatar
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 ...
Zareh Kasparian's user avatar
6 votes
1 answer
2k views

Yahoo blocked emails after changing mail server public IP address

We have two exchange edge server and we want to change their public IP addresses. Changing one of the server IP addresses (and related DNS records) was done successfully and emails are delivered to ...
harsini's user avatar
  • 251
0 votes
1 answer
105 views

Mailserver sufficient to pass as non-spam with Gmail

I am coming to the point of thinking this is beyond my ability to accomplish. I have repeatedly built new servers on Digital Ocean (3 so far) with Postfix, Dovecot, DKIM, pretty much everything out ...
Oliver Williams's user avatar
0 votes
2 answers
2k views

How to REJECT email using SpamAssassin

Is it possible to reject emails, like it is done in Postfix using header_checks, using SpamAssassin? Normally, the SpamAssassin only adds the spam flags and by default adds the word SPAM in the ...
Kaf's user avatar
  • 179
0 votes
0 answers
123 views

EC2/EIP email flagged as spam

My company is delivering email out of an ec2 instance using Postfix, but messages are sent to the spam folder in all major providers (Gmail, Outlook, Yahoo). We have an EIP associated with this ...
Billy Shears's user avatar
0 votes
0 answers
100 views

Postfix only forward catch all to stop spam

I have two catch all addresses set to forward to a gmail account and today i got a message from my hosting saying that they have blocked port 25 on my vps due to it sending spam out. how would i only ...
Ste Cox's user avatar
0 votes
0 answers
325 views

Mail issues only with Google App domains

I have a local mail server set up. It is connected via a dedicated IP (with an appropriate PTR record). I have DKIM, DMARC, and SPF set up. My domain has been added to Google's Postmaster Tools and ...
Joseph's user avatar
  • 153
2 votes
2 answers
1k views

Back up Rspamd Spam/Ham databases

I use Rspamd to filter my emails from spam. The spam filter has already been trained with more than 300.000 emails. Is there a way to save this "knowledge" or transfer it to another system?
br0ken.pipe's user avatar
0 votes
1 answer
73 views

Emails still going to Gmail & Hotmail spam after removing host from several blacklists

As I mentioned briefly in the subject the IP address of our mail server got blacklisted a while ago. One of the sites on the server got hacked, which resulted in the addition to a couple of blacklists....
Laurent's user avatar
  • 135
-2 votes
1 answer
121 views

Abuse report for spamming...abuse report [closed]

Few weeks ago, i activated on my server on automatic abuse report mail when someone try to brute force my SSH, i did it because i got an average of 3000 spamming IP each weeks. But today, my ISP send ...
redheness's user avatar
  • 216
1 vote
2 answers
319 views

Is this correct for a SPF record based on our setup?

Our company has a SMTP server that sends mail out on behalf of our customers. So a customer would log into our system, go to a specific section, and can fill out a form to send an Email to whoever ...
Thorin's user avatar
  • 209
1 vote
0 answers
58 views

Will enabling non-delivery notifications cause more spam?

In the past we received a lot of spam email. The past year it was a lot less and we would like to keep it that way offcourse. We are a construction company and we receive a lot of construction ...
Ramon Bakker's user avatar
0 votes
0 answers
726 views

My postfix server rejects my python script - "Client host rejected: cannot find your hostname"

I have a postfix on a server. When I'm trying to send an email from my python script, it gets rejected due to "Client host rejected: cannot find your hostname". How to allow an email come through? If ...
Immani's user avatar
  • 1
1 vote
2 answers
218 views

Prevent using spam trap e-mail address on registration

I am running a website where the users register using their e-mail addresses and receive a confirmation code before they can log in. (After this every contact is opt-in.) Every now and then some user ...
Gábor Héja's user avatar
3 votes
1 answer
141 views

Sender Score Low

We host our own email server and have discovered we have a low sending score that is causing delivery issues. From the report (senderscore.org), there is an IP address outside of the U.S. (email ...
Rocco The Taco's user avatar
1 vote
0 answers
380 views

Backscatter relay from Postfix backup mx server causing spam (553 5.7.1)

I have 2 Postfix Servers MAIN.mail.example.com BACKUP.mail.example.com Problem scenario: If spammer sends email from "me" to me directly to BACKUP, server forwards it to MAIN MAIN server reject ...
Marek Niesiobędzki's user avatar
0 votes
1 answer
969 views

SMTP Server All Records OK But All Email Sent in Spam

i bought a VPS with dedicated IP address and running windows Server 2012. I installed an SMTP server and DNS server, created all needed records: SPF, DMARC, DKIM, PTR, MX, and A. These results test ...
zobydeh karimi's user avatar
-2 votes
2 answers
3k views

"My domain" is being recognized as spammer for "no reason" [closed]

I linked my brand new domain, to yandex.connectand I sent only a few test emails, but NO email was sent or received. I checked many times the DNSs and they seem to be fine, When I send emails from ...
Fahed's user avatar
  • 121
0 votes
0 answers
101 views

Avoiding E-Mail spam filters (possibly based on originating computer?)

We recently started to send out a higher amount of E-Mails (invitations to a private event) to a select number of people. Now from some of those people using office365 for Mails, we were informed that ...
Lukski Lukilj's user avatar
0 votes
2 answers
1k views

Can a DMARC "reject" policy prevent NDR backscatter?

Our email is being spoofed. We already have SPF/DKIM/DMARC p="quarantine" policies in place however we are still receiving thousands of Non-Delivery Receipt (NDR) in our inbox. Will changing to DMARC ...
IMB's user avatar
  • 521
1 vote
0 answers
4k views

Our email server is spammed with "Returned mail: see transcript for details"

We are running a fairly popular online service and since this morning our email inbox is spammed with emails like this "Returned mail: see transcript for details" by "MAILER-DAEMON@localhost....
rewb0rn's user avatar
  • 27
6 votes
2 answers
2k views

Postfix: How to accept email with valid SPF but unresolvable hostname?

I have configured my Postfix to reject email sent from hosts without PTR record and hostnames that don't have A record. I found there are legitimate mail servers with valid SPF records which don't ...
LinuxBabe's user avatar
  • 1,035
0 votes
1 answer
181 views

Getting out of BRBL

About 1 year ago I installed a new webserver (Linux) and I got a new IP address for it. At that time the webserver could not send any email and the IP address had a good reputation. A few months ...
Lucio Crusca's user avatar