I use around 10 linux mailing servers for sending email marketing mails. My daily sending volume was around 1 to 5 million mails. I never had any problem regarding blocking of servers by vade or CSI. Around 3 months ago all my servers suddenly started getting blocked by Vade, CSI. I haven't changed anything in my mailing practice accept my 404 redirect file, the domains that I use to send emails are hosted on the IP which has infected 404 redirect file, which was replaced 3 months ago. When I tried to download the 404.php file in my windows laptop, it alerted me to a trojan virus within the 404 file.
My question is, using domains hosted on IP that has trojan infected 404 redirect can cause the mailing servers IP to get blocked by vade, csi?
So far I haven't been able to find out the cause of my mailing servers getting blocked. Only co-relation I can find is starting to use domains that are hosted on IP that has on trojan infected 404 redirect file.
Related
My Ubuntu based webserver needs to occasionally send emails. My python code is:
withsmtplib.SMTP('smtp-relay.gmail.com', 587, 'mydomain.com') as s:
s.sendmail(fromaddr, toaddr, msg.as_string())
s.quit()
I have
a Google workspace account
am using IP authentication (not SMTP auth)
my staging and production servers added as trusted IPs (staging is
local, production is cloud)
This setup had been working fine for 6+ months.
Two days ago I upgraded Ubuntu from 20LTS to 22LTS and python 3.8 to 3.10. Now the email is working fine on the staging server, but production keeps throwing:
Invalid credentials for relay [...]. The IP\n5.7.1 address you've registered in your G Suite SMTP Relay
service doesn't\n5.7.7 match domain of the account this email is being sent from. If you are\n5.7.1 trying to
relay mail from a domain that isn't registered under your G\n5.7.1 Suite account or has empty envelope-from,
you must configure your\n5.7.1 mail server either to use SMTP AUTH to identify the sending domain or\n5.7.1 to
present one of your domain names in the HELO or EHLO command. For\n5.7.1 more information, please visit
https://support.google.com/a/answer/6140680#invalidcred ...
Any suggestions?
Edit 1:
I fired up my old ubuntu server in the cloud. I added its new IP as trusted on Google. The email worked fine. I can think of only three possibilities
Google somehow recognizes and trusts requests coming from the old
device (even though it now has a different IP)
Linode is somehow not sending the correct IP address from my new
server
Something broke during the Ubuntu upgrade
I find each of the 3 possibilities quite bizarre and unbelievable at this point, but I'll keep researching.
PS: Three factoids that may/may not be relevant:
I upgraded the staging server in place. For production I spun a new
instance, made sure everything else was working fine (except
email) and then transferred IP from the existing instance to new
When I log in to my google admin account to edit trusted IP list, my
IP is the same as staging server. I don't think I have the same
option for production, since it's an Ubuntu server I manage through SSH
I found some comments online (none in official documentation), that
the reverse DNS needs to be setup before Google would relay anything.
I set up the entry about 20 hours ago for production, but still
getting the same error. And for my staging server, I don't have rDNS
and it still sends emails (it's accessible from the internet, but I
don't have a static IP)
PPS:
The sender email is someuser#mydomain.com (not #gmail.com)
The production server is hosted on linode.com
This post comes close
to discussing a similar situation, but that is focused more on
signing in. My setup uses IP authentication, not SMTP auth. Plus it was working fine until Friday (8/12)
It turned out to be a really frustrating issue. My best guess is that Linode's Ubuntu 22.04 repository has issues. We were thinking of migrating to AWS anyway, this gave us a strong impetus.
Anyway, here are some tips from my experience that a future reader might be able to benefit from
When you're using IP authentication for Google's SMTP relay, the updates are fairly quick. I ended up spinning at least 5 instances with 5 different IPs, and each time Google was able to trust my IP within 2-3 seconds (after I updated in workspace console)
Google didn't care about my reverse DNS entries. I had read some comments online that Google wouldn't relay without rDNS, but I didn't face any such problems (at least not any rDNS I was setting. The ISP or the cloud provider have a default entry, that was good enough - if Google was even looking for it). This one was particularly problematic because that information can take hours to propagate, and I kept thinking maybe my code will start to work tomorrow.
The error message I received from Google was pretty uninformative. I contacted Google support to see if they have access to anything more meaningful on the server side. They didn't - it was a waste of time
It was somewhat helpful to run a fake SMTP server to see what my client was sending. I got it from this post. I ran it for a setup that was working and one that wasn't. In my case, the communication received was identical. Though in hindsight maybe I would've seen some differences if I ran it on a remote server.
python -m smtpd -n -d -c DebuggingServer localhost:2500
When I go to https://mxtoolbox.com/diagnostic.aspx, enter my domain (pairofdocs.net), and click ‘Test email server’, I get the error message:
Connecting to 23.23.216.253
2/19/2021 9:23:30 AM Connection attempt #1 - Unable to connect after 15 seconds.
I have no idea why this is happening – any suggestions?
I have used the test previously and it worked. My domain is configured as follows:
DNS – on NameCheap.com
Web site (a simple one) – on Amazon Web Services
Email – handled by Zoho
I rebuilt my domain about six months ago, on a new AWS instance - whose IP address is 23.23.216.253, and do not recall the problem’s having happened prior to the rebuild.
Since your Email hosting is outsource to Zoho, there is a pretty good chance the email server has been setup correctly and has a pretty decent uptime.
It is likely the problem you are having is with how you are connecting to the email server although the error you've provided shows what seems to be an offline email server.
Setup: We have a mail server running exchange 2010 and a windows server 2011 for active directory. We also have a draytek router. I have access to all these things just not super familiar.
I work for a company as a junior IT tech so I have not set any of this up but need to find a solution. We're getting added to the spamhaus blocklist every other week or so.
What i've tried so far:
I have scanned the 30 computers with about 5 different virus scanners and mostly found minor things with malwarebytes which have been removed but we keep getting listed.
Also tried running netstat on each PC to monitor port 25 connections but none of the PC's checked seemed to be sending out of this port.
I have access to the router and can login to it and have heard about blocking port 25 but whenever I do this no one can send emails out. On the dreytek syslogs I can see an IP address from a virtual server that is 190.2.141.250 connecting to our main server on port 25 (SMPT). I suspect this is the thing that is sending out the spam but I can't find out how to block it.
I am kinda lost so any ideas would be appreciated
We have a VPS with CentOS combined with DirectAdmin which we use for a Magento shop. This runs fine, except for sending email.
Problem:
It appears that some specific domains won't receive our emails and we get a bounce. If we use any other email sending systems, the mails arrive without problems.
The bounce mail contains the following error:
SMTP error from remote mail server after HELO Company-Shops:
host mx-cluster-b2.one.com [IP ADRESS]: 504 5.5.2 :
Helo command rejected: need fully-qualified hostname
After googling and trying things for a week now, I am a bit lost. I tried checking postfix in CentOS, but this is not installed and I'm not quite sure if this is needed.
Possible issue?
I believe the hostfile in CentOS is setup incorrectly:
127.0.0.1 localhost localhost.localdomain localhost4 ... etc
OUR IP Company-Shops
'Company-Shops' should probably be a domain name, am I right? The same as the rDNS. But I'm afraid if I change this it will kill my site and whatnot. I'm not sure if this entry correlates with the 'company-Shops' helo label in the bounce error.
Some extra info:
- We use the webmail Roundcube from DirectAdmin
- At the moment we run one shop, but this might grow a bit (multiple sites on 1 IP)
- We don't use subdomains
- We've set up a reverse DNS, with the domain
Is there anyone with similiar experiences or with a bit more knowledge about this subject? I appreciate any advice we can get, as we are stuck..
Many thanks.
Yes, that's right: your mail server should identify itself using a fully-qualified domain name when it connects to send mail via SMTP. You don't say what mail server you're running, but since you're using DA, it's probably Exim. If so, you want to edit /etc/exim.conf and set primary_hostname to the FQDN of your server.
This would also be a good time to double-check that reverse DNS is set up properly for your IP address. Many hosts will also reject email from servers on IPs without a valid rDNS record.
I'm not familiar with Magento, but I can't see any way that changing the Exim configuration in this way could impact that program.
I've recently setup my Ubuntu web server with exim4 so my PHP website applications can send email such as "thank you" and "confirmation" notices.
I've got it setup and working such that I can send email to gmail, Yahoo! and my work address. However, my work email gets caught up in our spam filter. I'm new to setting up mail servers so I'm not sure what I might need to look for in making this mail server more trusted, while keeping is secure.
Here are some details:
Server is NATed behind a firewall.
Firewall has port 25 open for outgoing SMTP traffic (from server to anywhere).
Server is virtual hosting a couple different of our websites
The server is running the following exim4 config:
dc_eximconfig_configtype='internet'
dc_other_hostnames='web-serv.example1.com;example2.com'
dc_local_interfacees='127.0.0.1'
dc_readhost=''
dc_relay_domains=''
dc_minimaldns='false'
dc_relay_nets='' dc_smarthost=''
CFILEMODE='644'
dc_use_split_config='false'
Questions:
Do I need to open port 25 to incoming SMTP mail (anywhere to server)? I wonder if other mail servers need to talk to my mail server to verify itself, in a sort of handshake attempt.
I have not created any MX records primarily because the server has different websites on it the mail server should send mail for all the websites. Do I need to pick/create a domain address and create MX records for it?
One thing of note is that the mail headers look like this:
Return-Path: <www-data#example2.com>
Received: from web-serv.example1.com ([Firewall public IP Address])
Received-SPF: neutral (google.com: [Firewall public IP Address] is neither permitted nor denied by best guess record for domain of www-data#example2.com)
"web-serv" is the host name of the server, such that you get this if you type it into the command line:
$ hostname
web-serv
and "www-data" is the account name for the Apache2 server that Ubuntu gave it as default.
Any other general advice would be appreciated. It's all new to me.
Cheers!
One item of note, since I posted this question time time ago (almost 10 months) is that I found out the biggest issue I had was with setting up the DNS for reverse DNS on our hosting providers side of things.
In other words, our hosting provider (the people who give us our IP address and manage our hardware) had to enter a record to match my server(s) hostname to whatever IP address it used.
There's a specific name for this. I believe it's a "PTR" record but the name escapes me at the moment, but you basically tell them "my server hostname is ..." and they do a quick update to the DNS for reverse DNS purposes.
When I asked this question, we had a different hosting provider who didn't really help explain this to me, and after switching providers, I got to talk to someone who was happy to help me understand that side of the equation.
And as I understand it, this is setup by the people who assign you the IP addresses. But there's probably more to it than that.
Once I got that setup properly, email had no problem getting through the spam filters and Gmail/Yahoo showed SPF as "passed". It was showing neutral before.
Our company email was set to drop any email that would not resolve reverse DNS, which is why I could not even receive the email or find it in the spam filter. Of course, that situation would be dependent on the company and what email policy and software they're using to manage spam. Some might just drop all email that does not reverse DNS and some might dump it in to spam filters instead.
Hope that might help some people with similar issues.
Cheers!