On 10/18/2021 10:56 AM, Brandon Long wrote:
On Sat, Oct 16, 2021 at 2:35 PM Dave Crocker via mailop
<mailop@mailop.org <mailto:mailop@mailop.org>> wrote:
On 10/15/2021 5:40 PM, Grant Taylor via mailop wrote:
> The motivation for spreading service IPs across different /24
prefixes
> is so that if
The issue here is not the generic one of using multiple IPs. It is
about using them to separate IMAP from SMTP. That's an entirely
different matter.
To the extent that anyone claims that there is a reptuation-related
reason for this kind of separate, for this kind of service distinction,
they need to provide substantial detail that makes the validity of the
reason crystal clear.
I have not seen it specifically for IMAP and SMTP, but I have seen it
for SMTP and HTTP.
Indeed. Both of those get into the reputation game (and do need to.)
IMAP is used with an internal login. Separate reputation analysis, in
the style of an abuse filtering engine, doesn't make sense to me.
Specifically, I've seen people block http(s) access to an A record based
on a hostname pointed at it
being advertised in spam or if the smtp server and web server are
shared, ie they don't block by port
instead, they use a broad block in both directions.
Sure, if a bad actor -- who doesn't have to log in - connects to a
service, it makes sense to accumulate whatever reputation of them you
can, across services.
But as soon as the system connecting has to privately register with you,
for on-going access, I'd expect that to involve a /very/ different
assessment engine, since there is more and persistent knowledge about
them.
I suppose that knowing the connect from an address that is problematic
might be interesting, but, well... sigh.
I wouldn't be overly worried about it for IMAP, given that your IMAP
customers are likely quite different than
who they are mailing, so it seems the likely overlap of those blocks is
going to be small.
Exactly.
d/
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