Why do invitations from another S5 not come into my email or calendar?

[Floral]

When my husband sends an event on his S5, it doesn't come through on emails or calendars.
I had an S5 now S6 & problem is still there.
How do we fix this.

 

[B. Diddy]

See discussion in your other thread: http://forums.androidcentral.com/samsung-galaxy-s6/749896-calendar.html#post5584582. This thread closed to prevent parallel discussions.