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MTA

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  MTA Polyna-Maude Racicot-Summerside <debian@polynamaude.com> - 2021-07-05 15:30 +0200
    Re: MTA Greg Wooledge <greg@wooledge.org> - 2021-07-05 15:40 +0200
      Re: MTA Vincent Lefevre <vincent@vinc17.net> - 2021-07-05 16:00 +0200
        Re: MTA Greg Wooledge <greg@wooledge.org> - 2021-07-05 16:10 +0200
          Re: MTA Polyna-Maude Racicot-Summerside <debian@polynamaude.com> - 2021-07-05 16:30 +0200
            Re: MTA Vincent Lefevre <vincent@vinc17.net> - 2021-07-05 17:10 +0200
            Re: MTA John Hasler <john@sugarbit.com> - 2021-07-05 17:20 +0200
          Re: MTA Vincent Lefevre <vincent@vinc17.net> - 2021-07-05 16:50 +0200
            Re: MTA Joe <joe@jretrading.com> - 2021-07-05 22:40 +0200
      Re: MTA Polyna-Maude Racicot-Summerside <debian@polynamaude.com> - 2021-07-05 16:00 +0200
        Re: MTA Vincent Lefevre <vincent@vinc17.net> - 2021-07-05 16:00 +0200
          Re: MTA (corrected) Polyna-Maude Racicot-Summerside <debian@polynamaude.com> - 2021-07-05 16:40 +0200
            Re: MTA (corrected) Vincent Lefevre <vincent@vinc17.net> - 2021-07-05 17:10 +0200
              Re: MTA (corrected) Polyna-Maude Racicot-Summerside <debian@polynamaude.com> - 2021-07-05 17:50 +0200
              Re: MTA (corrected) Joe <joe@jretrading.com> - 2021-07-05 22:20 +0200
                Re: MTA (corrected) Vincent Lefevre <vincent@vinc17.net> - 2021-07-06 12:00 +0200
            Re: MTA (corrected) Greg Wooledge <greg@wooledge.org> - 2021-07-05 18:50 +0200
              Re: MTA (corrected) Greg Wooledge <greg@wooledge.org> - 2021-07-05 19:10 +0200
                Re: MTA (corrected) Polyna-Maude Racicot-Summerside <debian@polynamaude.com> - 2021-07-05 19:20 +0200
                  Re: MTA (corrected) Polyna-Maude Racicot-Summerside <debian@polynamaude.com> - 2021-07-09 22:20 +0200
              Re: MTA (corrected) Polyna-Maude Racicot-Summerside <debian@polynamaude.com> - 2021-07-05 19:10 +0200
      Re: MTA Joe <joe@jretrading.com> - 2021-07-05 22:10 +0200
    Re: MTA Joe <joe@jretrading.com> - 2021-07-05 22:30 +0200

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#236928 — Re: MTA (corrected)

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Hi

On 2021-07-05 12:46 p.m., Greg Wooledge wrote:
> On Mon, Jul 05, 2021 at 10:32:27AM -0400, Polyna-Maude Racicot-Summerside wrote:
>> This is a copy of the dump of my domain name config for CYRANIA.COM
>>
>> -------START
>>
> [snip]
> 
>> cyrania.com.	1	IN	A	162.213.253.79
> 
>> ;; MX Records
>> cyrania.com.	1	IN	MX	0 mail.cyrania.com.
> 
>> cyrania.com.	1	IN	TXT	"v=spf1 +ip4:162.213.253.79
>> +include:spf.web-hosting.com +ip4:198.54.120.203 ~all"
> 
> These are not the publically visible DNS records for your domain.
> 
> 
> unicorn:~$ host cyrania.com.
> cyrania.com has address 104.21.59.235
> cyrania.com has address 172.67.185.109
> cyrania.com has IPv6 address 2606:4700:3031::6815:3beb
> cyrania.com has IPv6 address 2606:4700:3031::ac43:b96d
> cyrania.com mail is handled by 0 _dc-mx.f1202d9a4fb3.cyrania.com.
> 
> unicorn:~$ host -t mx cyrania.com.
> cyrania.com mail is handled by 0 _dc-mx.f1202d9a4fb3.cyrania.com.
> 
> unicorn:~$ host -t txt cyrania.com.
> cyrania.com descriptive text "v=spf1 +ip4:162.213.253.79 +include:spf.web-hosting.com +include:premium58.web-hosting.com +ip4:198.54.120.203 ~all"
> 
> 
> The SPF record is pretty close, but the others are nowhere near.
> 
> It's also particularly disturbing that your MX record contains an
> underscore.  I've been led to believe that's disallowed in hostnames.
> Attempting to resolve it gives me this error:
> 
The file I published here was a dump done by Cloudflare some time ago.
Maybe I've modified the records since but I doubt it.

> unicorn:~$ host _dc-mx.f1202d9a4fb3.cyrania.com.
> _dc-mx.f1202d9a4fb3.cyrania.com has address 162.213.253.79
> Host _dc-mx.f1202d9a4fb3.cyrania.com not found: 3(NXDOMAIN)
> 
What you wrote (dc-mx) is not a underscore.
Also, I don't think I have such record in my domain (dc-mx) sounds to me
like a Microsoft thing (DC = Domain Controler, MX = Mail Exchange). I
only have a mail. and a MX record.

> Whether that's because of the underscore is unclear to me.
> 
> In any case, you're going to want to find out why your publically visible
> DNS records don't match what you thought they should be.
> 

Thanks, yes there's some part that may be different because some of them
are "proxied" by Cloudflare. So if a request is made to Cloudflare DNS
server, they'll give their own server DNS and this will be followed to
my server.

Cloudlfare offer in their free tier a service that will cache your web
pages and offer a fast service because they own many server closer to
the user (edge type service).

The problem is that the free tier is limited and seems to have
limitation that prevent some type of use. This is one of the reason that
pushes me to disable the Cloudflare on my mail domain name. Anyway, I
don't have a website on those domain and Namecheap is responsible of
their own security so no need for acceleration or DDOS on my side.

I'll let know when I did finish changing from Cloudflare to the standard
name management (DNS) offered by Namecheap. I'll see if this fix part of
my problem (like getting 5 DMARC email for every email I respond on the
list).

Thanks,
Sincerely,


-- 
Polyna-Maude R.-Summerside
-Be smart, Be wise, Support opensource development

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#236936

On Mon, 5 Jul 2021 09:35:22 -0400
Greg Wooledge <greg@wooledge.org> wrote:

> On Mon, Jul 05, 2021 at 09:23:03AM -0400, Polyna-Maude
> Racicot-Summerside wrote:
> > Reporting-MTA: dns; premium58.web-hosting.com
> > 
> > Action: failed
> > Final-Recipient: rfc822;bjoern.ricks@greenbone.net
> > Status: 5.0.0
> > Remote-MTA: dns; mail.greenbone.net
> > Diagnostic-Code: smtp; 550 X-Host-Lookup-Failed: Reverse DNS lookup
> > failed for 162.213.253.79 (failed)  
> 
> unicorn:~$ host 162.213.253.79
> 79.253.213.162.in-addr.arpa domain name pointer cyrania.com.
> unicorn:~$ host cyrania.com.
> cyrania.com has address 172.67.185.109
> cyrania.com has address 104.21.59.235
> cyrania.com has IPv6 address 2606:4700:3031::6815:3beb
> cyrania.com has IPv6 address 2606:4700:3031::ac43:b96d
> cyrania.com mail is handled by 0 _dc-mx.f1202d9a4fb3.cyrania.com.
> 
> Your "reverse" (PTR record for 162.213.253.79) doesn't match.  Which
> is to say, none of the "A" results from cyrania.com. match the
> original IP address of 162.213.253.79.
> 
> Some SMTP receivers may care about that.  Apparently the receiver for
> greenbone.net (whose name is mail.greenbone.net) is one of them.
> 

It's a pretty common requirement, as at one time it was the second best
spam defence (after accepting mail only for named users). Not so good
now that many ISPs are providing some kind of PTR record. But I haven't
deleted the check from my mail server...

-- 
Joe

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#236938

On Mon, 5 Jul 2021 09:23:03 -0400
Polyna-Maude Racicot-Summerside <debian@polynamaude.com> wrote:


> 
> I was thinking that maybe I should start thinking about hosting my own
> email server. But I wasn't sure if I felt like I had the nerve to do
> so. Some people say it's a lot of maintenance work.
> 

No, it's not a big deal. The only maintenance I do is to try to improve
my anti-spam measures, and that's probably less than half an hour per
year. *After* the mail server was set up and running properly, of
course, and even that doesn't take much work.

*If* you have a static IP address and your ISP is willing to keep the
CIDR block containing it off of blacklists (some ISPs don't care). It
can allegedly be done with a dynamic address, but you not only have to
keep the MX->A record updated, but also the PTR. You may not even have
control of the PTR on a dynamic address. It's more to go wrong, and
there is a chance of delayed mail whenever the address changes. Also,
some mail servers try to identify dynamic addresses and reject SMTP
connections from them. 

If you have a dynamic address, the only safe way is to send through a
smarthost with a good reputation, and many ISPs do not provide them
now. Also, you lose logging of sent mail, which is one of the reasons
for doing it yourself.

-- 
Joe

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