I have DDNS with no IP address (free) and its IP / target is 127.0.0.1 (localhost). Is it possible to use this domain as an E-mail server in the program such as Mercury or hMail? If so, how?
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How do you hide an origin server behind CloudFlare and still be able to send transactional emails via providers like Sendgrid, Mailgun, etc.?
My problem is that when I send an email it seems that a Received: from line is always added to the message, revealing my origin server's real IP.
I tried it with Sendgrid, both via JSON API and SMTP endpoints, but it's visible in both cases.
How do you solve this problem?
Are there some transactional email providers which do not append this line?
Do you use some complicated setup with a distributed message queue and a worker running on a different host with different IP, only for sending emails?
Do you connect to the providers via a proxy / VPN? Is there such a thing as proxy for SMTP?
In your case we recommend running your email through a different server. You can find some guidance in this KB article. If your IP is still leaked you should contact Cloudflare support.
Run email on separate server/service If you are running your mail on
the same server as your website, then the attacker can always find
your origin server IP. To close this possible security gap, you can
use an email service on a separate server than your website, whether
through your hosting provider or an outside service (e.g., Google
Apps).
For Mac users:
You can run this command in Terminal to see what IP is being reported
with your MX records:
dig +short $(dig mx +short WEBSITE) For example, if I was concerned
about example.com, I would enter:
dig +short $(dig mx +short example.com) The output will be an IP
address. This is the IP address that an attacker can always find. You
want to make sure this IP address is different that the IP address for
your web server. Otherwise, no matter how many times you change your
web server, if your email is also on the same server, then the
attacker can always find the new IP.
For PC users:
You can run this command in command prompt to see what IP is being
reported with your MX records:
nslookup -q=mx WEBSITE For example, if I was concerned about
example.com, I would enter:
nslookup -q=mx example.com The output will be an IP address. This is
the IP address that an attacker can always find. You want to make sure
this IP address is different that the IP address for your web server.
Otherwise, no matter how many times you change your web server, if
your email is also on the same server, then the attacker can always
find the new IP.
We are running sendmail-8.13.4 on AIX.
I need to update the configuration and make sendmail act as a relay client only, meaning it will only be used to send mail out of the host and NOT accept mail.
Here is my client.mc config:
include(`/usr/samples/tcpip/sendmail/m4/cf.m4')
VERSIONID(`sendmail config for aix7')
OSTYPE(`aixsample')dnl
MASQUERADE_AS(`myserver.com')dnl
FEATURE(`masquerade_envelope')dnl
FEATURE(`accept_unresolvable_domains')
FEATURE(`accept_unqualified_senders')
FEATURE(always_add_domain)dnl
FEATURE(`nullclient',`mail-relay.xxxx.myserver.com')dnl
define(`STATUS_FILE', `/etc/mail/statistics')dnl
define(`MAIL_HUB', `myserver.com.')dnl
define(`LOCAL_RELAY', `myserver.com.')dnl
We have an MS Exchange server, so we are basically using sendmail on a particular AIX host to forward all email to the exchange server and let Exchange handle everything.
The above configuration works fine for sending email to recipients
mail user#myserver.com
What I also need to do is be able to send the email with only specifying the alias part and not the domain, so if I do:
mail user (omitting the #myserver.com recipient domain part)
I want sendmail to append the #myserver.com in this situation where a domain is not given. Is this possible without maintaining some sort of alias/list file for every possible userid > userid#mydomain.com?
Thanks.
You can use approach mentioned in sendmail FAQ 4.22 - make sendmail accept smtp connections only on (local) loopback ip interface.
Sendmail FAQ 4.22 : Why can't I receive external mail?
It may be achieved by the following lines in sendmail.mc file used to generated sendmail.cf file:
dnl Do no listen on msa(587) port
FEATURE(`no_default_msa')dnl
dnl Listen on IPv6 loopback address
dnl DAEMON_OPTIONS(`Family=inet6, Name=MTA-v6, Port=smtp, Addr=::1')dnl
dnl Listen on IPv4 loopback address
DAEMON_OPTIONS(`Family=inet, Name=MTA-v4, Port=smtp, Addr=127.0.0.1')dnl
I have a VM instance on Google Compute Engine, which is running Windows Server 2012 R2. I have my Apache web server, PHP, MySQL, FTP, and various other things running great, easily accessible from the world. I installed MDaemon Messaging Server (Alt-N's email server), which I had on my old physical box for years. I am able to use port 110 just fine, but I simply cannot get SMTP to work. Yes, I'm well aware of (Compute Engine's Blocked SMTP Ports). Knowing these blocked google ports, I would like to choose port 2525 as Mdaemon's SMTP port. I added firewall rules on the server to allow it, and I added the Compute Engine Network port exceptions as well, and of course changed the Mdaemon's server settings for 2525. I still cannot send email. Hell, I even tried port 2626 and nadda.
I understand I could sign up through google's recommended "sendgrid" that would force me to use mail.sendgrid.com, port 2525, and have a maximum of 25,000 per month limit (on free sendgrid account), but I personally think it's ridiculous needing to sign up and have limits on email when I paid $2,400 for Mdaemon email server. I should be able to use my own domain's mail.mydomain.com and authenticate through MY email server, not sendgrid's.
Is there something simple I'm missing to be able to use my own email server software on my google compute engine VM instance? Or is it just fact that this is the right I give up by choosing google's cloud server services?
SMTP server, in your case MDaemon, sends all outbound emails directly to the recipient's mail servers on their inbound SMTP port which is 25. This is the port you will need to configure on your MDaemon's SMTP outbound port setting. So changing it to 2525 or 2626 won't help because recipient's SMTP servers usually do not listen on those ports.
As you also mentioned all outgoing traffic to port 25 (SMTP) is blocked on Compute Engine. Therefore you'll need to configure a smart host for your MDaemon message routing which listens on a non-blocked port. This is something like using a third party service (e.g. SendGrid).
I have a Ubuntu LAMP server in virtual box. I want to install postfix for sending and receiving mail using the server.
Is it compulsory to have a domain name to my ip address for installing postfix and using it for mailing purposes?
You should be able to set up Postfix for local forwarding/exchange with just an IP address - that should be no problem. Sending email to other email servers, however, probably won't work as many email servers do reverse DNS lookup on the FQDN to verify the server isn't on a blacklist somewhere.
I need a IM client that support yahoo and allow user to set yahoo IM server address.
Yahoo IM servers names (scs.msg.yahoo.com, scsa.msg.yahoo.com, scsb.msg.yahoo.com, scsc.msg.yahoo.com) are not accesible through my company LAN, so I should use IP addresses of their servers.
We can find ip of a domain name by simply pinging that domain name.
My problem was related to another network issue (port 443 was blocked) but initially I supposed that it relates to server ip address.