Envelope rewrite by sendmail?

[Trond Endrestøl]

On Wed, 25 Jan 2017 13:29-0800, Chuck Swiger wrote:

> On Jan 25, 2017, at 12:42 PM, Trond Endrestøl <Trond.Endrestol at fagskolen.gjovik.no> wrote:
> >  A mail messages arrives on the small SMTP server addressed to
> >  shorty at short.tld <mailto:shorty at short.tld>. Sendmail, though the aliases mechanism, forwards
> >  the message to long.name at some.incredible.long.domain.name.tld.
> > 
> >  Antispam measures such as SPF will flag the small SMTP server as not
> >  allowed to send email on behalf of the originator.
> 
> Yes.  You will need the admins of some.incredible.long.domain.name.tld
> to agree and whitelist your short.tld mailserver if you want it to be a trusted relay.
> 
> >  Thus, prior to forwarding each message, the small SMTP server will
> >  need to masquerade as the originator and rewrite the envelope's from
> >  address to an address within the short.tld domain.
> 
> Try not do that, unless both domains belong to you and share a common namespace for
> delivery including aliases.  Otherwise, From header munging will break various things,
> most commonly mailing lists and bounce handling processing.

Thank you for your input.

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