From Newsgroup: comp.misc

A client of mine has a customer that keeps mailboxes on outlook.com. But
if you look at the MX records for their domain, they point at
mimecast.com.

So staff at my client send an email to this customer (actually a reply to
a previous email from them) from their own domain, which has an SPF
record. Mimecast receives the mail, does something or other to it (I have
no idea what, and no interest in finding out), and tries to pass it on to outlook.com.

outlook.com sees the sender address for that mail is at my client’s
domain. Checking the corresponding SPF record, they see that nobody is authorized to send mail from that domain other than my client’s own
machines (of course). So the mail forwarded from Mimecast gets rejected.

Should my client (and myself) have to worry about internal mail screwups
at other companies? Seems to me, if this lot want to use both mimecast.com
and outlook.com, they need to have some way to tell their outlook.com
service to accept any and all mail forwarded from mimecast.com.

And if they can’t figure that out, it should be their problem, not ours.
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: comp.misc

On 06.09.2025 00:01 Uhr Lawrence D’Oliveiro wrote:

So staff at my client send an email to this customer (actually a
reply to a previous email from them) from their own domain, which has
an SPF record. Mimecast receives the mail, does something or other to
it (I have no idea what, and no interest in finding out), and tries
to pass it on to outlook.com.

outlook.com sees the sender address for that mail is at my client’s domain. Checking the corresponding SPF record, they see that nobody
is authorized to send mail from that domain other than my client’s
own machines (of course). So the mail forwarded from Mimecast gets
rejected.

Should my client (and myself) have to worry about internal mail
screwups at other companies? Seems to me, if this lot want to use
both mimecast.com and outlook.com, they need to have some way to tell
their outlook.com service to accept any and all mail forwarded from mimecast.com.

That domain has a crap configuration. If they want to route their mail
from mimecast to outlook, they need to configure outlook.com to ignore
SPF fails.
--
kind regards
Marco
Send spam to [email protected]
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: comp.misc

On Sat, 6 Sep 2025 10:45:24 +0200, Marco Moock wrote:

That domain has a crap configuration. If they want to route their mail
from mimecast to outlook, they need to configure outlook.com to ignore
SPF fails.

I thought of a sneaky idea: we could locally override their MX records,
and send mail for their domain directly to outlook.com ...
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: comp.misc

On 06.09.2025 09:26 Uhr Lawrence D’Oliveiro wrote:

On Sat, 6 Sep 2025 10:45:24 +0200, Marco Moock wrote:

That domain has a crap configuration. If they want to route their
mail from mimecast to outlook, they need to configure outlook.com
to ignore SPF fails.

I thought of a sneaky idea: we could locally override their MX
records, and send mail for their domain directly to outlook.com ...

If outlook.com accepts them. I dunno how that is configured. I
recommend telling their postmaster about this problem.
--
kind regards
Marco
Send spam to [email protected]
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: comp.misc

On Sat, 6 Sep 2025 12:17:28 +0200, Marco Moock wrote:

On 06.09.2025 09:26 Uhr Lawrence D’Oliveiro wrote:

On Sat, 6 Sep 2025 10:45:24 +0200, Marco Moock wrote:

That domain has a crap configuration. If they want to route their
mail from mimecast to outlook, they need to configure outlook.com
to ignore SPF fails.

I thought of a sneaky idea: we could locally override their MX
records, and send mail for their domain directly to outlook.com ...

If outlook.com accepts them.

You really think they could figure out how to set a restriction like
that, when they can’t figure out how to fix the SPF issue??
--- Synchronet 3.21a-Linux NewsLink 1.2