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Rewriting Reply-To header to match From Address??

 

 

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tnet.services at gmail

Jul 14, 2012, 1:54 PM

Post #1 of 5 (972 views)
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Rewriting Reply-To header to match From Address??

Looking into rewritting the Reply-To header...

Some info first:

We have a gateway server which does all the Internet mail transfers both in
and out. It has a number of domains it provides mail services for.

On some of the domains, the email is forwarded to specific user accounts to
an Inside mail server using the that mail servers hostname and the specific
userid for that mailbox on that server (not always the same as the inbound
local part for that user using their domain).

So, lets say we have a user name fred with an Internet Email address of:
fred [at] got-here

Email arrives and gets queued for the inside mail server for
fred123 [at] inside

Everything is cool... The user gets the email using whatever protocol they
use and when they send email, it authenticates with the inside mail server
with that same address, and sets in the email their Internet email address (
fred [at] got-here in this case).

When it gets to the outside mail server it looks like:

Reply-To: fred123 [at] inside
From: fred [at] got-here

However, once the message leaves the outside mail server, the Reply-To
header is bogus since there is no Internet known host called
inside.zipturtle.com so it would never get back to the gateway server
should it have to go several hops.

All of the examples that I see of rewriting deal with the same domain. In
this case the inside and gateway server using a completely different domain
than the email address involved. The From address is correct, but the
Reply-To headers make no sense after the email leaves the mail gateway.

Hope this makes sense.
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mike.tubby at thorcom

Jul 15, 2012, 4:14 AM

Post #2 of 5 (918 views)
Permalink
Re: Rewriting Reply-To header to match From Address?? [In reply to]

Kevin,

Rather than re-write the Reply-To: header why not just strip it off? The
Reply-To header is used in preference to the From: for the return
address, if it exists - but there's no requirement for it - AFAIK.

Manipulating headers:

http://wiki.exim.org/FAQ/Headers

Mike


On 14/07/2012 21:54, Kevin wrote:
> Looking into rewritting the Reply-To header...
>
> Some info first:
>
> We have a gateway server which does all the Internet mail transfers both in
> and out. It has a number of domains it provides mail services for.
>
> On some of the domains, the email is forwarded to specific user accounts to
> an Inside mail server using the that mail servers hostname and the specific
> userid for that mailbox on that server (not always the same as the inbound
> local part for that user using their domain).
>
> So, lets say we have a user name fred with an Internet Email address of:
> fred [at] got-here
>
> Email arrives and gets queued for the inside mail server for
> fred123 [at] inside
>
> Everything is cool... The user gets the email using whatever protocol they
> use and when they send email, it authenticates with the inside mail server
> with that same address, and sets in the email their Internet email address (
> fred [at] got-here in this case).
>
> When it gets to the outside mail server it looks like:
>
> Reply-To: fred123 [at] inside
> From: fred [at] got-here
>
> However, once the message leaves the outside mail server, the Reply-To
> header is bogus since there is no Internet known host called
> inside.zipturtle.com so it would never get back to the gateway server
> should it have to go several hops.
>
> All of the examples that I see of rewriting deal with the same domain. In
> this case the inside and gateway server using a completely different domain
> than the email address involved. The From address is correct, but the
> Reply-To headers make no sense after the email leaves the mail gateway.
>
> Hope this makes sense.



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Chris.Knadle at coredump

Jul 15, 2012, 2:17 PM

Post #3 of 5 (913 views)
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Re: Rewriting Reply-To header to match From Address?? [In reply to]

On Sunday, July 15, 2012 07:14:34, Michael J. Tubby B.Sc G8TIC wrote:
> Kevin,
>
> Rather than re-write the Reply-To: header why not just strip it off? The
> Reply-To header is used in preference to the From: for the return
> address, if it exists - but there's no requirement for it - AFAIK.

It may not be a requirement, but stripping the Reply-To: header is likely make
it more difficult for users to deal with mailing lists, because I think a
Reply will default to being sent to the author rather than the mailing list.

-- Chris

--
Chris Knadle
Chris.Knadle [at] coredump


> On 14/07/2012 21:54, Kevin wrote:
> > Looking into rewritting the Reply-To header...
> >
> > Some info first:
> >
> > We have a gateway server which does all the Internet mail transfers both
> > in and out. It has a number of domains it provides mail services for.
> >
> > On some of the domains, the email is forwarded to specific user accounts
> > to an Inside mail server using the that mail servers hostname and the
> > specific userid for that mailbox on that server (not always the same as
> > the inbound local part for that user using their domain).
> >
> > So, lets say we have a user name fred with an Internet Email address of:
> > fred [at] got-here
> >
> > Email arrives and gets queued for the inside mail server for
> > fred123 [at] inside
> >
> > Everything is cool... The user gets the email using whatever protocol
> > they use and when they send email, it authenticates with the inside mail
> > server with that same address, and sets in the email their Internet
> > email address ( fred [at] got-here in this case).
> >
> > When it gets to the outside mail server it looks like:
> >
> > Reply-To: fred123 [at] inside
> > From: fred [at] got-here
> >
> > However, once the message leaves the outside mail server, the Reply-To
> > header is bogus since there is no Internet known host called
> > inside.zipturtle.com so it would never get back to the gateway server
> > should it have to go several hops.
> >
> > All of the examples that I see of rewriting deal with the same domain.
> > In this case the inside and gateway server using a completely different
> > domain than the email address involved. The From address is correct,
> > but the Reply-To headers make no sense after the email leaves the mail
> > gateway.
> >
> > Hope this makes sense.


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nigel at dotdot

Jul 16, 2012, 1:40 AM

Post #4 of 5 (913 views)
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Re: Rewriting Reply-To header to match From Address?? [In reply to]

Chris Knadle wrote:
> On Sunday, July 15, 2012 07:14:34, Michael J. Tubby B.Sc G8TIC wrote:
>> Kevin,
>>
>> Rather than re-write the Reply-To: header why not just strip it off? The
>> Reply-To header is used in preference to the From: for the return
>> address, if it exists - but there's no requirement for it - AFAIK.
>
> It may not be a requirement, but stripping the Reply-To: header is likely make
> it more difficult for users to deal with mailing lists, because I think a
> Reply will default to being sent to the author rather than the mailing list.

I personally would still strip any Reply-To: with an internal domain in
it - fixing it is hard work and liable to unexpected results, stripping
it is easy. If people want Reply-To: then they should use valid
addresses in them.

In general, a setup that mangles email addresses in headers is already
skipping through a mine field. Just think about header signing...

Nigel.


--
[ Nigel Metheringham ------------------------------ nigel [at] dotdot ]
[ Ellipsis Intangible Technologies ]


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Chris.Knadle at coredump

Jul 17, 2012, 7:42 AM

Post #5 of 5 (916 views)
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Re: Rewriting Reply-To header to match From Address?? [In reply to]

On Monday, July 16, 2012 04:40:58, Nigel Metheringham wrote:
> Chris Knadle wrote:
> > On Sunday, July 15, 2012 07:14:34, Michael J. Tubby B.Sc G8TIC wrote:
> >> Kevin,
> >>
> >> Rather than re-write the Reply-To: header why not just strip it off? The
> >> Reply-To header is used in preference to the From: for the return
> >> address, if it exists - but there's no requirement for it - AFAIK.
> >
> > It may not be a requirement, but stripping the Reply-To: header is likely
> > make it more difficult for users to deal with mailing lists, because I
> > think a Reply will default to being sent to the author rather than the
> > mailing list.

I just realized what I wrote above most likely isn't relevant, because the
only time this would be an issue is if an internal mail server was /running/ a
mailing list. Outgoing mail going /to/ a mailing list usually has a Reply-To:
of the sender.

> I personally would still strip any Reply-To: with an internal domain in
> it - fixing it is hard work and liable to unexpected results, stripping
> it is easy. If people want Reply-To: then they should use valid
> addresses in them.

I think I agree with this now.

-- Chris

--
Chris Knadle
Chris.Knadle [at] coredump

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