crashes with MailKit sample app

Number:rdar://FB12794488 Date Originated:2023-07-30
Status:Resolved Resolved:2024-01-22
Product:macOS Mail Product Version:
Classification:Bug Reproducible:
Compiled the MailKit sample app ( and dropped it into my Applications folder. This Mac hasn't used Mail up until now but I enabled it Mail > Settings > Extensions > "SampleMailExtensions" then the app would crash after a few seconds. App doesn't crash if SampleMailExtensions is disabled.

Crashed Thread:        7  Dispatch queue: MCTaskHandler queue"

Someone else has a similar on-startup crash with the sample MailKit Mail Extension enabled in Mail. His crashes on startup. His seems to crash in "Dispatch queue: IMAPNetworkTaskHandler queue (QOS: BACKGROUND)" which is slightly different than the crash I reported above.

Likely related to MEMessageSecurityHandler?

macOS Ventura 13.6, Sonoma 14.0 beta 6


Resolved in Sonoma 14.3


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