OT: Outlook oddities
campbell at cnpapers.com
Mon Mar 8 17:10:40 GMT 2010
Glenn Steen wrote:
> On 8 March 2010 15:53, Steve Campbell <campbell at cnpapers.com> wrote:
>> Just wondering if anyone ever experiences email sent by Outlook senders that
>> have no "From" in the envelop? The headers seem to have the proper "From"
>> entry. These get caught quite often by MS (actually SA) with a "no watermark
>> or sender address". They are sent from our users, which normally get
>> whitelisted by IP address. The problem doesn't always happen even from the
>> same sender.
>> Thanks and sorry for the OT
>> Steve Campbell
> The empty sender (MAIL FROM:<>) is a valid sender reserved for the
> mail system itself. Typically used for delivery reports (or rather
> "non-delivery":-). Since all mail coming into your system having an
> empty sender need be in response to a mail sent from you, MailScanner
> (not SA) adds a watermark header... The "returning MTA" is supposed to
> preserve that in the reply/DSN/NDN, so MailScanner checks for that and
> stamps any mail lacking a watermark, or having a forged one, as spam.
> So you need look a bit harder on from where you get these, and in what
> situations;-). It's probably doing just the thing it should:-);-)
Yep, I agree it looks like valid mail and all and that the headers and
envelop are probably valid for certain types of email. But...
All of our users are NATted to one IP address from our internal network
to the outgoing mailserver. These emails show that they have arrived
properly from that internal network. These are real emails sent from our
users. They just don't have the "From" in them and, as you stated, they
don't have the proper Return-Path (it's blank). They show only one hop
to the mailserver and it's from the proper NATted IP.
So I guess the question is: Why, if all email from our users takes the
same path, do only Outlook users exhibit this problem and only
occasionally? It never shows up from Thunderbird, OE, or any other mail
I'll dig a little deeper, but was just hoping some of you had run across
Thanks for the reply.
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