You can view and edit your contacts within Mailspring! Just choose Window > Contacts from the app’s main menu. Mailspring supports Google Contacts and CardDAV, an open standard used by iCloud, FastMail, and others.

How often do contacts sync?

Mailspring syncs your address book with your provider about every 45 minutes. (Google places a daily cap on API requests, so syncing more often isn’t practical.) Quitting and relaunching Mailspring syncs your contacts immediately.

Which accounts have an editable address book?

Contacts are synced for Google accounts and for any account whose provider offers CardDAV (iCloud, Fastmail, Yahoo, Posteo, Nextcloud, and most hosted mail). Microsoft 365 and Outlook.com don't expose contacts this way, so those accounts only show Found in Mail. If you added a Google account a long time ago and can't edit contacts, select it in Preferences > Accounts and click Re-authenticate... to grant the extra permission.

Adding and editing contacts

Open Window > Contacts, select an account's All Contacts in the sidebar (the button reads Select an account to add a contact until you do), and click New Contact. Select a contact to Edit or Delete it from the toolbar or the right-click menu.

Groups (distribution lists)

Hover over an account in the Contacts sidebar and click + to create a group, then drag contacts onto it. Right-click a group to rename or delete it, and right-click a contact to Remove from Group. When composing, type the group's name in the To field and choose it to address everyone in the group.

Importing and exporting

Use Contact > Import vCards... (or drop .vcf files onto the contact list) to import into the selected CardDAV account; Google contacts must be imported at contacts.google.com because Google doesn't accept vCards from clients. Export All vCards... and Export Selected... write standard .vcf files you can bring to any other app.

"Found in Mail"

Each account also has a Found in Mail list of everyone you've corresponded with, which feeds autocomplete. You can turn it off per account with the Disable button at the top of that list. To remove stale suggestions, Preferences > General > Reset Cache rebuilds it from your mail.