duplicate subject lines in headers (again)

Mark Sapiro mark at msapiro.net
Thu Nov 3 03:22:48 UTC 2016

On 11/02/2016 08:22 AM, Warwick Brown wrote:
> I have that historic issue of sending email to yahoo due to duplicate
> subject lines.

Huh? Can you be more specific about what the issue is? If by
"historical" you mean something in the archives, a link to an archived
thread may help.

> I can see there is a work-around of setting “Multiple Headers” from
> “add” to “append”, but I was wondering whether there was any appetite to
> get it fixed?

Again, what exactly is the issue. Does the Multiple Headers setting
actually affect Subject: headers.

> Also - what exactly are the implications for using “append” as opposed
> to “add” because there seems to be some anecdotal comments regarding
> breaking DKIM.

If an incoming message has MailScanner headers and those headers are
DKIM signed, changing them in any way or adding additional headers with
the same name will break the DKIM sig. On the other hand, if those
headers have a different org-name in the X-%org-name%-MailScanner
prefix, Multiple Headers = append or replace will modify those headers
and break the DKIM sig, but add will add new headers with a different
org-name and won't affect the existing DKIM sig.

But then, many other transformations will break the DKIM sig anyway -
things like tagging the Subject: or modifying the message body in any
way, e.g. by disarming web bugs.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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