Resolve error message 17199 in Mac Outlook 2011

Outlook 2011 on Mac refuses to send anything, every attempt logging error 17199. Receiving continues normally and nothing about our account changed that I know of.

What does 17199 govern and what is the fix sequence?

Error 17199 is Outlook 2011's sending pipeline failing to reach or satisfy the outgoing server, and receiving fine tells us the account and network live, narrowing it to the send specific settings and state. Nothing changed that you know of usually means something changed server side, providers adjust outgoing requirements without ceremony and 2011 era defaults age badly against them. Fix sequence:

1

Verify the outgoing settings against current requirements: Tools, Accounts, select the account and click More Options under the outgoing server. Modern providers want authentication set to use the incoming credentials and an SSL port, commonly 465 or 587 with Override default port ticked, rather than the ancient port 25 defaults 2011 setups often still carry.

2

Check whether Outlook wedged itself offline for sending: the Outlook menu, Work Offline toggle, cycle it off and on, then retry a send. The 2011 send queue occasionally sticks in a state this cycle clears.

3

Clear a stuck outbox: a malformed draft at the queue's head, often one with a huge attachment or a corrupted recipient, blocks everything behind it with this same error. Open the Outbox, delete or rebuild the oldest item and watch whether the rest flow.

4

Persisting past all three, rebuild the identity via the Microsoft Database Utility, hold Option while launching Outlook, since send queue state lives in the identity database and rebuilds cure its corruption. The dedicated identity thread linked alongside walks that procedure fully.

Same closing note as every 2011 thread deserves: the client is unsupported and providers keep raising outgoing requirements, notably retiring the older TLS versions 2011 speaks, so a 17199 that resists everything above may be the provider having moved permanently beyond the client. The mail itself always remains portable through OLM export and conversion whenever that day arrives.

Our provider had indeed retired plain port 25 the previous week. Switched to 587 with SSL and authentication and the whole stuck outbox flushed immediately.