Re: [CentOS] Mail server troubles

[Jonathan Billings]

On Fri, Oct 09, 2020 at 02:23:20PM -0500, Valeri Galtsev wrote:
> Not for my users, thank you. My authenticated users send whatever they want
> without any filtering, scoring, scanning for virii (that is Latin plural for
> virus).

It might interest you to know that the plural for 'virus' is
'viruses'.  The latin word it was derived from was a neuter term, so
you might say 'vira', but since it was derived from what meant
'poison' (like the word virulent) there wasn't really a plural used.
Also, the Romans hadn't figured out Germ Theory yet so they didn't
know it was composed of multiple small entities.  Also, the word
'Viri' is the plural of the masculine word 'Vir' for 'Male human', so
it is confusing. ('vir' used in the words 'triumvir' or 'virile' /
'virility') 

Chuck 'virii' in the bin with words like 'octopi'.

-- 
Jonathan Billings 
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Re: [CentOS] Mail server troubles

[Valeri Galtsev]

On 2020-10-09 14:16, Kenneth Porter wrote:
--On Friday, October 09, 2020 6:29 PM +1300 Rob Kampen 
 wrote:



If this reject is due to their spam filtering process, it is actually the
email author's problem - how they make up their sentences, key words etc.
and thus the problem will travel with them, to whatever email provider
they choose.

Suggest they get educated in how to write an appropriate email that
doesn't raise alarms, or they could use mailchimp (e.g. only) for their
large group emails.


Good point. Feed all your outbound mail to SpamAssassin


Not for my users, thank you. My authenticated users send whatever they 
want without any filtering, scoring, scanning for virii (that is Latin 
plural for virus).


But if there is problem created by my user, it definitely will be 
properly addressed, with user, in person.


Valeri

and set it to 
retain the report in the output, directed to a local email account so 
you can review it via Dovecot. You could also direct it to an external 
mail account (eg. on a VPS) so you can see what it looks like to the 
outside world.




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--

Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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Re: [CentOS] Mail server troubles

[Kenneth Porter]

--On Friday, October 09, 2020 6:29 PM +1300 Rob Kampen 
 wrote:



If this reject is due to their spam filtering process, it is actually the
email author's problem - how they make up their sentences, key words etc.
and thus the problem will travel with them, to whatever email provider
they choose.

Suggest they get educated in how to write an appropriate email that
doesn't raise alarms, or they could use mailchimp (e.g. only) for their
large group emails.


Good point. Feed all your outbound mail to SpamAssassin and set it to 
retain the report in the output, directed to a local email account so you 
can review it via Dovecot. You could also direct it to an external mail 
account (eg. on a VPS) so you can see what it looks like to the outside 
world.




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Re: [CentOS] Mail server troubles

[Kenneth Porter]

--On Friday, October 09, 2020 12:49 AM +0200 Nicolas Kovacs 
 wrote:



This is probably a bit OT, but here goes.


I suggest subscribing to the Mailop list and then looking at the archives. 
Very low traffic, comparable to the CentOS users list.




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Re: [CentOS] Mail server troubles

[Phil Perry]

On 09/10/2020 16:42, Ian Pilcher wrote:

On 10/8/20 4:49 PM, Nicolas Kovacs wrote:
The school's not happy because in their eyes I'm faulty of badly 
maintaining

their mail server.


As someone with school age children, I've observed that schools seem to
have a vastly over-inflated view of the importance of their
communications.  I've provided my email address to my children's schools
as an EMERGENCY contact method, and I've been receiving notifications of
every single fund raising activity, athletic event, PTA meeting, etc.,
etc., ever since - despite multiple complaints.

It seems likely to me that the school's emails are being reported as
spam by their recipients.  Tell them to look in the mirror.



Further, you need to explain to them that *you* are only responsible for 
the policies which dictate which emails *you* accept. You can not 
mandate other people to accept your mail. It is their mail server and 
they are completely within their rights to run it how they see fit, and 
they will.


Of course one hopes you are following industry best practices to aid 
your deliverability, but ultimately you are not in control of what 
others are willing to accept. If they do not understand this, flip it 
around and ask them how they feel about a spammer insisting you accept 
their spam and deliver it to all the staff and pupils.


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Re: [CentOS] Mail server troubles

[Ian Pilcher]

On 10/8/20 4:49 PM, Nicolas Kovacs wrote:

The school's not happy because in their eyes I'm faulty of badly maintaining
their mail server.


As someone with school age children, I've observed that schools seem to
have a vastly over-inflated view of the importance of their
communications.  I've provided my email address to my children's schools
as an EMERGENCY contact method, and I've been receiving notifications of
every single fund raising activity, athletic event, PTA meeting, etc.,
etc., ever since - despite multiple complaints.

It seems likely to me that the school's emails are being reported as
spam by their recipients.  Tell them to look in the mirror.

--

 In Soviet Russia, Google searches you!


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Re: [CentOS] Mail server troubles

[Simon Matter]

> Hi,
>
> This is probably a bit OT, but here goes.
>
> I've been running our local school's mail server since 2013, with mail
> addresses for school staff and some teachers. The server is running CentOS
> 7
> with Postfix and Dovecot, and it's a nice no-bullshit configuration with
> SPF,
> DKIM and DMARC.
>
> The school sends quite a lot of email out to parents, and sometimes, mail
> gets
> rejected:
>
> --8<
> : host smtp-in.orange.fr[193.252.22.65] said: 550
> 5.2.0
> Mail rejete. Mail rejected. ofr_506 [506] (in reply to end of DATA
> command)
>
> : host smtp-in.orange.fr[193.252.22.65] said: 550
> 5.2.0
> Mail rejete. Mail rejected. ofr_506 [506] (in reply to end of DATA
> command)
> --8<
>
> This happens randomly with the usual suspects among crappy mail providers
> like
> Orange, Hotmail/Live, Yahoo and the rest.
>
> The school's not happy because in their eyes I'm faulty of badly
> maintaining
> their mail server.

In recent years I've got the impression that the big players do everything
to make people move to their platform and stop providing their own email
systems. And being the admin of email systems can be a real PITA these
days.

What can be helpful is to check the reputation of your own servers with
services of some big player like https://talosintelligence.com/ and if all
is ok, it's a good reason to report to those who think it's your fault.

Regards,
Simon

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Re: [CentOS] Mail server troubles

[Rob Kampen]

On 9/10/20 11:08 am, Stephen John Smoogen wrote:

On Thu, 8 Oct 2020 at 17:50, Nicolas Kovacs  wrote:


Hi,

This is probably a bit OT, but here goes.

I've been running our local school's mail server since 2013, with mail
addresses for school staff and some teachers. The server is running CentOS
7
with Postfix and Dovecot, and it's a nice no-bullshit configuration with
SPF,
DKIM and DMARC.

The school sends quite a lot of email out to parents, and sometimes, mail
gets
rejected:

--8<
: host smtp-in.orange.fr[193.252.22.65] said: 550
5.2.0
 Mail rejete. Mail rejected. ofr_506 [506] (in reply to end of DATA
command)

: host smtp-in.orange.fr[193.252.22.65] said: 550
5.2.0
 Mail rejete. Mail rejected. ofr_506 [506] (in reply to end of DATA
command)
--8<

This happens randomly with the usual suspects among crappy mail providers
like
Orange, Hotmail/Live, Yahoo and the rest.



So wanadoo and orange seem to send a ofr_506 because the scanned mail was
found to be SPAM. This is independent of DKIM, SPF, DMARC but from them
scanning the email in the DATA and saying nope. Usually that is because too
many people complained about a set of email and the weight of email with
that content is getting blocked. I don't know if the school moving to
another provider will fix that as this isn't because of the IP it was sent
from (they block before the DATA is sent in that case). [My guess is that
someone wants to move to something else and is using this as the Casus
Belli to do so. ]

I don't really have a suggestion or solution to either problem..

If this reject is due to their spam filtering process, it is actually 
the email author's problem - how they make up their sentences, key words 
etc. and thus the problem will travel with them, to whatever email 
provider they choose.


Suggest they get educated in how to write an appropriate email that 
doesn't raise alarms, or they could use mailchimp (e.g. only) for their 
large group emails.


Just a final thought - are the email address headers containing multiple 
email addresses? this too can trigger blocking by some providers.


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Re: [CentOS] Mail server troubles

[Stephen John Smoogen]

On Thu, 8 Oct 2020 at 17:50, Nicolas Kovacs  wrote:

> Hi,
>
> This is probably a bit OT, but here goes.
>
> I've been running our local school's mail server since 2013, with mail
> addresses for school staff and some teachers. The server is running CentOS
> 7
> with Postfix and Dovecot, and it's a nice no-bullshit configuration with
> SPF,
> DKIM and DMARC.
>
> The school sends quite a lot of email out to parents, and sometimes, mail
> gets
> rejected:
>
> --8<
> : host smtp-in.orange.fr[193.252.22.65] said: 550
> 5.2.0
> Mail rejete. Mail rejected. ofr_506 [506] (in reply to end of DATA
> command)
>
> : host smtp-in.orange.fr[193.252.22.65] said: 550
> 5.2.0
> Mail rejete. Mail rejected. ofr_506 [506] (in reply to end of DATA
> command)
> --8<
>
> This happens randomly with the usual suspects among crappy mail providers
> like
> Orange, Hotmail/Live, Yahoo and the rest.
>
>
So wanadoo and orange seem to send a ofr_506 because the scanned mail was
found to be SPAM. This is independent of DKIM, SPF, DMARC but from them
scanning the email in the DATA and saying nope. Usually that is because too
many people complained about a set of email and the weight of email with
that content is getting blocked. I don't know if the school moving to
another provider will fix that as this isn't because of the IP it was sent
from (they block before the DATA is sent in that case). [My guess is that
someone wants to move to something else and is using this as the Casus
Belli to do so. ]

I don't really have a suggestion or solution to either problem..


>

-- 
Stephen J Smoogen.
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[CentOS] Mail server troubles

[Nicolas Kovacs]

Hi,

This is probably a bit OT, but here goes.

I've been running our local school's mail server since 2013, with mail
addresses for school staff and some teachers. The server is running CentOS 7
with Postfix and Dovecot, and it's a nice no-bullshit configuration with SPF,
DKIM and DMARC.

The school sends quite a lot of email out to parents, and sometimes, mail gets
rejected:

--8<
: host smtp-in.orange.fr[193.252.22.65] said: 550 5.2.0
Mail rejete. Mail rejected. ofr_506 [506] (in reply to end of DATA command)

: host smtp-in.orange.fr[193.252.22.65] said: 550 5.2.0
Mail rejete. Mail rejected. ofr_506 [506] (in reply to end of DATA command)
--8<

This happens randomly with the usual suspects among crappy mail providers like
Orange, Hotmail/Live, Yahoo and the rest.

The school's not happy because in their eyes I'm faulty of badly maintaining
their mail server.

So my question to you: do any of you guys running mail servers have similar
experiences? And how do you cope with it?

Cheers,

Niki
-- 
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7, place de l'église - 30730 Montpezat
Site : https://www.microlinux.fr
Blog : https://blog.microlinux.fr
Mail : i...@microlinux.fr
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Mob. : 06 51 80 12 12
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