XEPs (XMPP Extension Protocol) support:

Fully supported:
XEP-0022: Message Events (Superseded by XEP-0085)
XEP-0066: Out of Band Data
XEP-0077: In-Band Registration
XEP-0091: Delayed Delivery (Superseded by XEP-0203)
XEP-0092: Software Version
XEP-0199: XMPP Ping

Partially supported:
XEP-0030: Service Discovery
XEP-0045: Multi-User Chat (Entity Use Cases and Occupant Use Cases)
XEP-0054: vcard-temp
XEP-0082: XMPP Date and Time Profiles
XEP-0085: Chat State Notifications
XEP-0203: Delayed Delivery