Dear Young,
Thank you for your reply.
1. We use a custom application which writes 192x192 PNG's into the AD using LDAP.
2. I was told that the photos did show up in Outlook and Lync, but they're not when checking it myself.
I've just checked Lync, Outlook 2013 and OWA, there are no photos.
3. All photos, except for the ones that are manually added (not through the AD)
4. More than a week ago
I've asked the user who told me the photos are visible in Outlook and Lync for some screenshots.
Kind regards,
Roel