Autodiscover and Multiple SMTP namespaces

I have been asked recently for the required steps to configure Autodiscover when having Multiple SMTP namespaces, I have started writing few lines then upon checking my favorites I found a great bunch of blogs which explains the two possible solutions in great details, so here we go:

 

 

https://www.msexchange.org/articles_tutorials/exchange-server-2010/management-administration/exchange-autodiscover.html

https://blogs.technet.com/b/jmayans/archive/2006/09/07/454716.aspx

https://blogs.msdn.com/b/brad_hughes/archive/2007/12/18/autodiscover-http-redirect-method-using-isa-instead-of-a-second-web-site.aspx

https://www.more2know.nl/2010/05/18/exchange-autodiscover-and-multiple-domains/

 

background:

https://technet.microsoft.com/en-us/library/bb332063(EXCHG.80).aspx

https://support.microsoft.com/default.aspx?scid=kb;EN-US;940881