Outlook.com Max Connections

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Outlook.com Max Connections

Greg Sims
I placed the following post from Wietse in our main.cf -- let's call
this "mx_access":

# There is a crude way to automatically group messages by destination
# MX hosts, but that works only for the special case that all messages
# have exactly one recipient or all recipients in the same domain.
#
# /etc/postfix/main.cf:
#     check_recipient_mx_access pcre:/etc/postfix/mx_access
#
# /etc/postfix/mx_access:
#     /\.outlook\.com$/ FILTER outlook:
#     # other patterns...
#
# That will send a message to outlook if any MX looks like outlook.

We want to use our Postfix setup for the devotion email (always
exactly one recipient) AND transactional email which is unpredictable.
The words "crude" and "special case" are a bit unnerving for the
transactional email use case.  What happens if we use "mx_access" and
a transaction email arrives with multiple recipients of different
domains?  If I can gain confidence about the side-effects of using
"mx_access", I will likely switch from our current "transport_maps"
approach to "mx_access" for two reasons: truly dynamic as Viktor
points out and a much simpler/smaller map file.

Thanks, Greg
www.RayStedman.org
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Re: Outlook.com Max Connections

Wietse Venema
Greg Sims:

> I placed the following post from Wietse in our main.cf -- let's call
> this "mx_access":
>
> # There is a crude way to automatically group messages by destination
> # MX hosts, but that works only for the special case that all messages
> # have exactly one recipient or all recipients in the same domain.
> #
> # /etc/postfix/main.cf:
> #     check_recipient_mx_access pcre:/etc/postfix/mx_access
> #
> # /etc/postfix/mx_access:
> #     /\.outlook\.com$/ FILTER outlook:
> #     # other patterns...
> #
> # That will send a message to outlook if any MX looks like outlook.
>
> We want to use our Postfix setup for the devotion email (always
> exactly one recipient) AND transactional email which is unpredictable.
> The words "crude" and "special case" are a bit unnerving for the
> transactional email use case.  What happens if we use "mx_access" and
> a transaction email arrives with multiple recipients of different
> domains?  If I can gain confidence about the side-effects of using

The FILTER action overrides the routing of all recipients of a
message. For example, if one message has outlook and non-outlook
recipients, then all recipients would be sent to outlook.com,
including the non-outlook ones.

        Wietse

> "mx_access", I will likely switch from our current "transport_maps"
> approach to "mx_access" for two reasons: truly dynamic as Viktor
> points out and a much simpler/smaller map file.
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Re: Outlook.com Max Connections

Greg Sims
> The FILTER action overrides the routing of all recipients of a
> message. For example, if one message has outlook and non-outlook
> recipients, then all recipients would be sent to outlook.com,
> including the non-outlook ones.

Pardon my next question in advance.  Will outlook.com reliably relay
the message to recipients that do not have an outlook.com domain?

Blessings, Greg
www.RayStedman.org


Blessings, Greg
www.RayStedman.org


On Tue, Sep 8, 2020 at 4:09 PM Wietse Venema <[hidden email]> wrote:

>
> Greg Sims:
> > I placed the following post from Wietse in our main.cf -- let's call
> > this "mx_access":
> >
> > # There is a crude way to automatically group messages by destination
> > # MX hosts, but that works only for the special case that all messages
> > # have exactly one recipient or all recipients in the same domain.
> > #
> > # /etc/postfix/main.cf:
> > #     check_recipient_mx_access pcre:/etc/postfix/mx_access
> > #
> > # /etc/postfix/mx_access:
> > #     /\.outlook\.com$/ FILTER outlook:
> > #     # other patterns...
> > #
> > # That will send a message to outlook if any MX looks like outlook.
> >
> > We want to use our Postfix setup for the devotion email (always
> > exactly one recipient) AND transactional email which is unpredictable.
> > The words "crude" and "special case" are a bit unnerving for the
> > transactional email use case.  What happens if we use "mx_access" and
> > a transaction email arrives with multiple recipients of different
> > domains?  If I can gain confidence about the side-effects of using
>
> The FILTER action overrides the routing of all recipients of a
> message. For example, if one message has outlook and non-outlook
> recipients, then all recipients would be sent to outlook.com,
> including the non-outlook ones.
>
>         Wietse
>
> > "mx_access", I will likely switch from our current "transport_maps"
> > approach to "mx_access" for two reasons: truly dynamic as Viktor
> > points out and a much simpler/smaller map file.
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Re: Outlook.com Max Connections

Viktor Dukhovni
> On Sep 8, 2020, at 11:34 PM, Greg Sims <[hidden email]> wrote:
>
> Pardon my next question in advance.  Will outlook.com reliably relay
> the message to recipients that do not have an outlook.com domain?

No.  They'll reject "foreign" recipients.  There are work-arounds,
but you should not go there.  If your traffic includes multi-recipient
mail do not implement this "recipient restrictions" filter .

However, it can be safely added via:

        smtpd_data_restrictions =
                check_recipient_mx_access ...

Which will only apply to single-recipient messages.  Multi-recipient
messages (including those with some "outlook.com" recipients) will
bypass the filter, because "data restrictions" only expose a recpient
to test when the message has exactly one recipient.

--
        Viktor.