Can't Deliver to Microsoft Outlook Users, Even Thought My Email was Requested
Microsoft Outlook is one of the dominant email hosting platforms, used by large business gaming users, and Univerisities everywhere in North America.
There are many reasons why an address might be delivered but never inbox, or be rejected altogether. One of the most important ones is, do your recipients have THIS turned on:
Have your recipients open their Outlook and:
1) Go to Settings > View all Outlook settings > Mail > Junk email.
2) Under Filters, make sure the option "Only trust email from addresses in my Safe senders and domains list and Safe mailing lists" is turned off.
This will allow Outlook to use its own spam detection algorithms and not block everything else.
IF so, you need to get them to turn that off through some other way such as a marketing campaign or on your signup form when they opt-in to your mailings.
Supporting Information at Microsoft: