Nobody thinks of email as journaling, but look at your sent folder: it's the most complete written record of your life that exists. What you promised, argued, arranged, apologized for — dated and timestamped, in your own words. It just lives in the wrong app.
Retrography can mirror it into your timeline. The connection is plain IMAP, which means it works with almost any provider — Gmail, iCloud (including custom domains), Fastmail, your own server. You give it the host, your username, and an app password; the password goes into the iOS Keychain and the connection runs straight from your phone to your mail server. There is no middleman — no server of ours ever sees a single message.
You choose the scope. Sent only is the quiet default worth trying first: your outgoing mail is the part you authored, and it reads like a diary you didn't know you were keeping. Or include the inbox too — on Gmail, a Primary-only filter keeps Promotions, Social and the rest of the noise categories out of your life story, which is exactly where they don't belong. The app even learns your “me” addresses from the Sent folder, so aliases and send-as addresses are attributed correctly.
On the day page, mail appears as a compact box — who, what, which direction — next to the places you went and the photos you took. The Tuesday you closed the apartment, the day you emailed them back after two years: it's all one story now, told in the same place.