An HTTP Proxy in an ImapFlow Connection

Add ImapFlow’s proxy option to an existing IMAP connection and check whether the intermediary permits the mailbox port.

Add proxy alongside the mailbox settings when ImapFlow should reach an IMAP server through an HTTP CONNECT proxy:

import { ImapFlow } from 'imapflow';

const client = new ImapFlow({
  host: 'imap.example',
  port: 993,
  secure: true,
  auth: mailboxCredentials,
  proxy: 'http://proxy.example:8080',
});

mailboxCredentials holds the application's IMAP account. Use this client for the existing connect, mailbox work and logout or failure-cleanup sequence. For a publicly reachable mail service where a public intermediary is permitted, the HTTP proxy list supplies candidates for the proxy URL without proxy credentials; check access to the actual IMAP host and port.

Two details worth checking

  • The tunnel port is 993. The proxy must permit CONNECT to imap.example:993. An intermediary allowing website tunnels only on 443 can reject this request even with valid proxy credentials.
  • The mailbox remains TLS-protected. secure: true applies to the mailbox connection. The proxy URL's http scheme identifies the intermediary listener, not a replacement for the IMAP hostname.

If the intermediary needs a login, supply its account through ImapFlow's supported proxy URL format. Keep the mailbox account in auth. This example uses the standard Node proxy path; ImapFlow's custom runtime transport cannot be combined with proxy.

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