Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix

phenomlab

@DownPW said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

a postfix to secure the email.

Postfix by default will attempt TLS opportunistic knocking - a process that determines which protocols the receiving host will allow and will then perform a handshake which establishes contact based on those protocols (provided both ends support it - which in most cases, they do). Security between connecting domains is typically certificate based, although you require one certificate minimum for each domain you will be connecting to. As you can imagine, this is not really feasible unless you forward all mail to a relay host and secure that channel with a certificate.

However, at that point, you are trusting the relay host to send the email in a secure manner which may not always be the case.

@DownPW said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

OK so how to test to see if it works correctly ?

By default, each domain created in Virtualmin will have a corresponding email account for each domain. For example

As you can see from this example, there is a mail account added here. By default, Virtualmin based domains have email which is accessible at https://yourserver.com:20000 where you can login to that same portal, and access mail sent and received for that domain.

If you wanted to define the below

SMTP_HOST=xxxx.example.com
SMTP_FROM=xxxx@example.com
SMTP_FROM_NAME=xxxx
SMTP_PORT=587

It could look something like the below

SMTP_HOST=vps.mydomain.com # This is the name of the Virtualmin instance itself
SMTP_FROM=user@mydomain.com # Change this to the sender email address you want to use
SMTP_FROM_NAME=xxxx # Change this to the sender name, for example, "John Smith"
SMTP_PORT=587  # Change this to the port number that the server will answer on. Postfix by default will listen on a variety of ports, with 587 being one of them.

@DownPW said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

and I look at the postfix config in virtualmin, but I don’t see what values are declared.

You should not have to modify Postfix in any way unless there is a specific reason to do so.

@DownPW said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

And I still have DNS configuration problems at Cloudflare

By this, do you mean the absence of DKIM, DMARC and SPF or other issues?

DownPW

@phenomlab said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

By this, do you mean the absence of DKIM, DMARC and SPF or other issues?

yes and MX too

phenomlab

@DownPW said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

yes and MX too

Ok. MX is the base requirement for mail to be delivered in any circumstance, and all DNS zone files should have a least one entry. For example:

The MX record root.phenomlab.com is my VPS server, and yours ideally would be something similar. MX records require a weight based preference to determine order (in my case, 10), and it’s possible to have multiple - for example, 20 would be used to define the next in the list if the primary record is not available.

In terms of Cloudflare DNS, an example of this is below

There are a number of quality free tools that can help you create DMARC, SPF, and DKIM records as shown below

DownPW

@phenomlab said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

By default, Virtualmin based domains have email which is accessible at https://yourserver.com:20000

hmmm acess seem to work, I log with root but Inbox doesn’t seem to load correctly.

After a moment I have this message :

If I log with my root account like always, I have this :

EDIT: seems Ok with other account. Seems root account doesn’t have inbox

@phenomlab said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

The MX record root.phenomlab.com is my VPS server

what is root.phenomlab.com on your virtualmin? it’s not a virtual server, jsut your hostname i guess

For example, I am login to virtualmin on adm.xxxx.fr (hostname of my server) so my mx field should be adm.xxxx.fr and not root.xxxx.fr right?

for dmarc and dkim, i’am not see for the moment, i see later

— EDIT:

my Dmarc configuration

DownPW

DMARC =

v=DMARC1;p=reject;sp=reject;pct=100;rua=mailto:xxxxxxx@xxxxxxx.fr;ruf=mailto:xxxxxxx@xxxxxxx.fr;ri=86400;aspf=s;adkim=s;fo=1;

What do you think about it ?

For DKIM, I don’t quite understand. Once generated in the tools you gave, I understand for the DNS entry in CF but what do I do with the private and public key?

DownPW

Ok I have test to send an email with usermin. No error but email but I don’t receive the email

DownPW

Ok I have test to send an email with usermin. No error but email but I don’t receive the email

See this to mail queue :

/var/log/mail.log

Feb 20 21:26:24 adm postfix/smtp[674993]: E1205627B7: to=<xxxxxxxxxx@caramail.com>, relay=none, delay=4339, delays=4279/0.03/60/0, dsn=4.4.1, status=deferred (connect to mx00.caramail.com[212.227.15.30]:25: Connection timed out)
Feb 20 21:26:24 adm postfix/smtp[674993]: connect to mx00.caramail.com[212.227.15.30]:25: Connection timed out

Very strange. I’ll stop there for tonight.

phenomlab

@DownPW that looks like the port (25) is unreachable. Have you configured the firewall in your Virtualmin server to permit this outbound traffic? Similarly, do you have any other firewall type device between the server and the Internet which could be dropping packets?

DownPW

no Hetzner firewall configured
no crowdsec

I have just firewalld of virtualmin by default. I have add 25 and 587 port. Same problem

other log :

Feb 20 21:40:11 adm postfix/smtpd[679903]: disconnect from unknown[45.129.14.179] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Feb 20 21:40:11 adm postfix/smtpd[679903]: warning: unknown[45.129.14.179]: SASL LOGIN authentication failed: authentication failure
Feb 20 21:40:05 adm postfix/smtpd[679903]: connect from unknown[45.129.14.179]
Feb 20 21:40:05 adm postfix/smtpd[679903]: warning: hostname 179.hosted-by.198xd.com does not resolve to address 45.129.14.179
Feb 20 21:39:54 adm postfix/smtpd[679911]: disconnect from unknown[45.129.14.179] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Feb 20 21:39:54 adm postfix/smtpd[679911]: warning: unknown[45.129.14.179]: SASL LOGIN authentication failed: authentication failure
Feb 20 21:39:50 adm postfix/smtpd[679903]: disconnect from unknown[45.129.14.128] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Feb 20 21:39:50 adm postfix/smtpd[679903]: warning: unknown[45.129.14.128]: SASL LOGIN authentication failed: authentication failure
Feb 20 21:39:47 adm postfix/smtpd[679911]: connect from unknown[45.129.14.179]
Feb 20 21:39:47 adm postfix/smtpd[679911]: warning: hostname 179.hosted-by.198xd.com does not resolve to address 45.129.14.179
Feb 20 21:39:39 adm postfix/smtpd[679903]: connect from unknown[45.129.14.128]
Feb 20 21:39:39 adm postfix/smtpd[679903]: warning: hostname 128.hosted-by.198xd.com does not resolve to address 45.129.14.128
Feb 20 21:39:38 adm postfix/smtpd[679911]: disconnect from unknown[45.129.14.179] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Feb 20 21:39:37 adm postfix/smtpd[679911]: warning: unknown[45.129.14.179]: SASL LOGIN authentication failed: authentication failure
Feb 20 21:39:32 adm postfix/smtpd[679903]: disconnect from unknown[45.129.14.128] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Feb 20 21:39:32 adm postfix/smtpd[679903]: warning: unknown[45.129.14.128]: SASL LOGIN authentication failed: authentication failure
Feb 20 21:39:30 adm postfix/smtpd[679911]: connect from unknown[45.129.14.179]
Feb 20 21:39:30 adm postfix/smtpd[679911]: warning: hostname 179.hosted-by.198xd.com does not resolve to address 45.129.14.179
Feb 20 21:39:24 adm postfix/smtpd[679903]: connect from unknown[45.129.14.128]
Feb 20 21:39:24 adm postfix/smtpd[679903]: warning: hostname 128.hosted-by.198xd.com does not resolve to address 45.129.14.128
Feb 20 21:39:22 adm postfix/smtp[679066]: 1AD316278E: to=<xxxxxxxxxxxx@gmail.com>, relay=none, delay=3410, delays=3260/0.03/150/0, dsn=4.4.1, status=deferred (connect to alt2.gmail-smtp-in.l.google.com[2a00:1450:4025:c03::1a]:25: Connection timed out)
Feb 20 21:39:22 adm postfix/smtp[679066]: connect to alt2.gmail-smtp-in.l.google.com[2a00:1450:4025:c03::1a]:25: Connection timed out
Feb 20 21:39:19 adm postfix/smtpd[679911]: disconnect from unknown[45.129.14.179] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Feb 20 21:39:19 adm postfix/smtpd[679911]: warning: unknown[45.129.14.179]: SASL LOGIN authentication failed: authentication failure
Feb 20 21:39:17 adm postfix/smtpd[679903]: disconnect from unknown[45.129.14.128] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Feb 20 21:39:16 adm postfix/smtpd[679903]: warning: unknown[45.129.14.128]: SASL LOGIN authentication failed: authentication failure
Feb 20 21:39:12 adm postfix/smtpd[679911]: connect from unknown[45.129.14.179]
Feb 20 21:39:12 adm postfix/smtpd[679911]: warning: hostname 179.hosted-by.198xd.com does not resolve to address 45.129.14.179
Feb 20 21:39:08 adm postfix/smtpd[679903]: connect from unknown[45.129.14.128]
Feb 20 21:39:08 adm postfix/smtpd[679903]: warning: hostname 128.hosted-by.198xd.com does not resolve to address 45.129.14.128
Feb 20 21:39:02 adm postfix/smtpd[679911]: disconnect from unknown[45.129.14.179] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Feb 20 21:39:01 adm postfix/smtpd[679911]: warning: unknown[45.129.14.179]: SASL LOGIN authentication failed: authentication failure
Feb 20 21:39:01 adm postfix/smtpd[679903]: disconnect from unknown[45.129.14.128] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Feb 20 21:39:00 adm postfix/smtpd[679903]: warning: unknown[45.129.14.128]: SASL LOGIN authentication failed: authentication failure
Feb 20 21:38:55 adm postfix/smtpd[679911]: connect from unknown[45.129.14.179]
Feb 20 21:38:55 adm postfix/smtpd[679911]: warning: hostname 179.hosted-by.198xd.com does not resolve to address 45.129.14.179
Feb 20 21:38:53 adm postfix/smtpd[679903]: connect from unknown[45.129.14.128]
Feb 20 21:38:53 adm postfix/smtpd[679903]: warning: hostname 128.hosted-by.198xd.com does not resolve to address 45.129.14.128
Feb 20 21:38:52 adm postfix/smtp[679066]: connect to alt1.gmail-smtp-in.l.google.com[2a00:1450:4013:c16::1b]:25: Connection timed out
Feb 20 21:38:44 adm postfix/smtpd[679903]: disconnect from unknown[45.129.14.128] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
Feb 20 21:38:43 adm postfix/smtpd[679903]: warning: unknown[45.129.14.128]: SASL LOGIN authentication failed: authentication failure
Feb 20 21:38:38 adm postfix/smtpd[679903]: connect from unknown[45.129.14.128]
Feb 20 21:38:38 adm postfix/smtpd[679903]: warning: hostname 128.hosted-by.198xd.com does not resolve to address 45.129.14.128
Feb 20 21:38:22 adm postfix/smtp[678126]: 73987627BE: to=<xxxxxxxxxxxxxxxxxxxxxxxx@gmail.com>, relay=none, delay=3350, delays=3200/0.03/150/0, dsn=4.4.1, status=deferred (connect to alt2.gmail-smtp-in.l.google.com[2a00:1450:4025:c03::1a]:25: Connection timed out)
Feb 20 21:38:22 adm postfix/smtp[678126]: connect to alt2.gmail-smtp-in.l.google.com[2a00:1450:4025:c03::1a]:25: Connection timed out
Feb 20 21:38:22 adm postfix/smtp[679066]: connect to alt1.gmail-smtp-in.l.google.com[142.250.153.26]:25: Connection timed out
Feb 20 21:37:52 adm postfix/smtp[678126]: connect to alt1.gmail-smtp-in.l.google.com[2a00:1450:4013:c16::1b]:25: Connection timed out
Feb 20 21:37:52 adm postfix/error[679677]: 20D20627C1: to=<xxxxxxxxxxxxxxx@caramail.com>, relay=none, delay=5027, delays=4967/60/0/0.01, dsn=4.4.1, status=deferred (delivery temporarily suspended: connect to mx01.caramail.com[217.72.192.76]:25: Connection timed out)
Feb 20 21:37:52 adm postfix/error[679676]: 225BB627B7: to=<xxxxxxxxxxxxxxxxx@caramail.com>, relay=none, delay=3784, delays=3724/60/0/0, dsn=4.4.1, status=deferred (delivery temporarily suspended: connect to mx01.caramail.com[217.72.192.76]:25: Connection timed out)
Feb 20 21:37:52 adm postfix/smtp[679070]: 1ED2A627AB: to=<xxxxxxxxxxxxxxxx@caramail.com>, relay=none, delay=4432, delays=4372/0.08/60/0, dsn=4.4.1, status=deferred (connect to mx00.caramail.com[212.227.15.30]:25: Connection timed out)
Feb 20 21:37:52 adm postfix/smtp[679070]: connect to mx00.caramail.com[212.227.15.30]:25: Connection timed out
Feb 20 21:37:52 adm postfix/error[679676]: 1FBDB627B3: to=<xxxxxxxxxxxxxxxx@caramail.com>, relay=none, delay=3500, delays=3440/60/0/0.01, dsn=4.4.1, status=deferred (delivery temporarily suspended: connect to mx01.caramail.com[217.72.192.76]:25: Connection timed out)
Feb 20 21:37:52 adm postfix/smtp[679069]: 1DE7B62796: to=<xxxxxxxxxxxxxx@caramail.com>, relay=none, delay=4587, delays=4527/0.07/60/0, dsn=4.4.1, status=deferred (connect to mx01.caramail.com[217.72.192.76]:25: Connection timed out)
Feb 20 21:37:52 adm postfix/smtp[679068]: 1D536627AE: to=<xxxxxxxxxxxxxxxx@caramail.com>, relay=none, delay=4531, delays=4471/0.05/60/0, dsn=4.4.1, status=deferred (connect to mx01.caramail.com[217.72.192.76]:25: Connection timed out)
Feb 20 21:37:52 adm postfix/smtp[679067]: 1C5D3627B6: to=<xxxxxxxxxxxxxxxxxxx@caramail.com>, relay=none, delay=3815, delays=3755/0.04/60/0, dsn=4.4.1, status=deferred (connect to mx00.caramail.com[212.227.15.30]:25: Connection timed out)
Feb 20 21:37:52 adm postfix/smtp[679069]: connect to mx01.caramail.com[217.72.192.76]:25: Connection timed out
Feb 20 21:37:52 adm postfix/smtp[679068]: connect to mx01.caramail.com[217.72.192.76]:25: Connection timed out
Feb 20 21:37:52 adm postfix/smtp[679067]: connect to mx00.caramail.com[212.227.15.30]:25: Connection timed out
Feb 20 21:37:52 adm postfix/smtp[679066]: connect to gmail-smtp-in.l.google.com[142.250.110.27]:25: Connection timed out
Feb 20 21:37:22 adm postfix/smtp[678126]: connect to alt1.gmail-smtp-in.l.google.com[142.250.153.26]:25: Connection timed out
Feb 20 21:37:22 adm postfix/smtp[679070]: connect to mx01.caramail.com[217.72.192.76]:25: Connection timed out
Feb 20 21:37:22 adm postfix/smtp[679069]: connect to mx00.caramail.com[212.227.15.30]:25: Connection timed out
Feb 20 21:37:22 adm postfix/smtp[679068]: connect to mx00.caramail.com[212.227.15.30]:25: Connection timed out
Feb 20 21:37:22 adm postfix/smtp[679067]: connect to mx01.caramail.com[217.72.192.76]:25: Connection timed out
Feb 20 21:37:22 adm postfix/smtp[679066]: connect to gmail-smtp-in.l.google.com[2a00:1450:400c:c0b::1b]:25: Connection timed out
Feb 20 21:37:05 adm postfix/anvil[677271]: statistics: max cache size 3 at Feb 20 21:27:30
Feb 20 21:37:05 adm postfix/anvil[677271]: statistics: max connection count 1 for (smtp:45.88.90.174) at Feb 20 21:27:05
Feb 20 21:37:05 adm postfix/anvil[677271]: statistics: max connection rate 4/60s for (smtp:45.129.14.128) at Feb 20 21:28:06
Feb 20 21:36:52 adm postfix/smtp[678126]: connect to gmail-smtp-in.l.google.com[142.250.110.27]:25: Connection timed out

DownPW

Seems port 25 OK

phenomlab

@DownPW said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

For example, I am login to virtualmin on adm.xxxx.fr (hostname of my server) so my mx field should be adm.xxxx.fr and not root.xxxx.fr right?

Yes, correct.

@DownPW said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

For DKIM, I don’t quite understand. Once generated in the tools you gave, I understand for the DNS entry in CF but what do I do with the private and public key?

The private and public key can simply be stored. You do not have to do anything with these.

phenomlab

@DownPW said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

Seems port 25 OK

Not sure about that - see below from your server. When sending a telnet request on port 25, there is no response. This typically means the port is closed on your side.

What SHOULD happen is this

However, it DOES respond on port 587

From recollection, your VPS is being hosted by Hetzner. Although you have no firewall rules in place to prevent outbound connections on port 25, Hetzner by default will block this port until you’ve paid at least one month’s billing, and will only release the block if you formally request it. You’ll need to get the port unblocked before you can proceed - see below

https://docs.hetzner.com/cloud/servers/faq/#why-can-i-not-send-any-mails-from-my-server

Unfortunately, email spammers and scammers like to use cloud hosting providers. And we at Hetzner naturally want to prevent this. That’s why we block ports 25 and 465 by default on all cloud servers. This is a very common practice in the cloud hosting industry because it prevents abuse. We want to build trust with our new customers before we unblock these mail ports. Once you have been with us for a month and paid your first invoice, you can create a limit request to unblock these ports for a valid use case. In your request, you can tell us details about your use case. We make decisions on a case-by-case basis.

As an alternative, you can also use port 587 to send emails via external mail delivery services. Port 587 is not blocked and can be used without sending a limit request.

DownPW

OUPS

Ok so I think it’s Hetzner who is blocking.
I will make them an unblocking request.

phenomlab

@DownPW Yep

DownPW

Indeed. +1 for telnet.

I just trusted the netstats which told me that everything is OK which is certainly the case on the server.

since I didn’t have Telnet on hand I tested a website which told me OK

phenomlab

@DownPW said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

since I didn’t have Telnet on hand I tested a website which told me OK

I have to confess, I installed the telnet-client on your server for diagnostic purposes.

phenomlab

@DownPW said in Tutorial for secure emailing with personal domain,Cloudflare, virtualmin and postfix:

I will make them an unblocking request.

Curious to know how you got on with this…

DownPW

sorry for the late response my friends. They unblocked port 25 very quickly and I can send emails;

Just that the domains in caramail.com refused my sending of email for obscure reasons and protonmail, I receive them but in spam with an error message

I will share all its errors with you to see and I would like to deepen that the DMARC, and DKIM puts the private/public key which I do not really understand (see my request above)

https://sudonix.org/post/8462

phenomlab

@DownPW emails are going to junk because of missing DNS records as I mentioned previously. You won’t need to use the public and private keys unless you need extended and/or advanced functions.

DownPW

I have the DNS pointers present

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