By 31 October 2017, Outlook 2007 customers will need to upgrade to a newer version of Office to maintain mail connectivity via Outlook.
Why is this happening?
On Oct 31, 2017, RPC over HTTP will be deprecated in Exchange Online in favour of MAPI over HTTP, a modern protocol that was launched in May 2014. This change affects customers running Outlook 2007 because it won’t work with MAPI over HTTP. To continue email connectivity, Outlook 2007 customers must update to a newer version of Outlook or use Outlook on the web.
What is RPC over HTTP? What happens on October 31, 2017?
RPC over HTTP, also known as Outlook Anywhere, is a legacy method of connectivity and transport between Outlook for Windows and Exchange. In May 2014, Microsoft introduced MAPI over HTTP as a replacement for RPC over HTTP.
On October 31, 2017, Exchange Online mailboxes in Office 365 will require connections from Outlook for Windows to use MAPI over HTTP. Outlook for Windows clients that use RPC over HTTP (for example, Outlook 2007) will be unable to access Exchange Online mailboxes.
If you have any further questions, please do not hesitate to contact your DSM Account Manager.