What is suggestd on a Mac, and why does it read my mail?
suggestd finds contacts and events in Mail and Messages to suggest them elsewhere. It idled at 2 MB here. Why it spikes after a mail sync, and how to switch it off.
What is suggestd?
suggestd reads Mail and Messages on the device for things worth suggesting: a phone number to add to a contact, a flight to put in Calendar, an address for Maps. It lives in /System/Library/PrivateFrameworks/CoreSuggestions.framework and runs as you. On ours it used 2 MB and no CPU.
Why is suggestd using CPU?
New mail or messages to read: a new account, years of history arriving on a new Mac, or a large import. It settles once it has caught up.
How do I turn it off?
Open System Settings, Siri, Siri Suggestions and Privacy (wording varies by version), choose Mail or Messages, and turn off the suggestion and learning options for that app. The analysis happens on the device either way.
Related processes: knowledge-agent and duetexpertd.
See it live
Free Mac's System tab ranks every process by processor use and energy impact, once a second, and marks the ones macOS will not let you quit as protected. See also corespotlightd.
Related: searchpartyd and rapportd.
Common questions
What is suggestd on a Mac?
A macOS process that finds contacts, events and addresses in Mail and Messages to suggest them in other apps.
Does suggestd send my mail anywhere?
Its analysis runs on the device.
How do I stop suggestd?
Turn off suggestions and learning for Mail and Messages in System Settings, Siri.