Custom IMAP

Herald connects to mail through IMAP and sends mail through SMTP. The TUI talks to a backend interface; provider-specific details live in the config and IMAP/SMTP clients.

Provider presets

Known presets fill IMAP and SMTP host and port values when you have not provided explicit values:

Provider	IMAP	SMTP
Gmail	imap.gmail.com:993	smtp.gmail.com:587
Proton Mail Bridge	127.0.0.1:1143	127.0.0.1:1025
Fastmail	imap.fastmail.com:993	smtp.fastmail.com:587
iCloud	imap.mail.me.com:993	smtp.mail.me.com:587
Outlook	outlook.office365.com:993	smtp.office365.com:587

Manual config

credentials:
  username: "your@email.com"
  password: "your-password-or-app-password"
server:
  host: "imap.example.com"
  port: 993
smtp:
  host: "smtp.example.com"
  port: 587

Use provider-specific app passwords when your mail service requires them. Proton Mail users should run Proton Mail Bridge locally and use the Bridge-generated username and password.

Cache path

Herald stores a SQLite cache path in config:

cache:
  database_path: "herald/cached/conf.db"

If the path is missing, Herald creates a per-config cache path and writes it back to the YAML file. This prevents different account configs from sharing one working-directory database.

Sync behavior

Herald uses IMAP IDLE when available and falls back to polling. Cached rows can render quickly while live IMAP work continues, so startup stays usable even when a mailbox is large.