React Native

Fetch a Set of POP3 Messages by UIDL

Demonstrates the Chilkat MailMan.FetchUidlSet method, which retrieves the messages whose UIDLs are listed in a StringTable and appends them to an EmailBundle. The arguments are the UIDL StringTable, headersOnly, numBodyLines, and the EmailBundle. This example fetches two specific messages by UIDL.

Background: This is the efficient way to download a selected subset of a mailbox in one call — exactly the pattern for an incremental client: list the mailbox UIDLs, compare against the ones you've already stored, and fetch only the new UIDLs as a set. It avoids re-downloading messages you already have while still pulling everything new in a single operation.

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import { Email, EmailBundle, MailMan, StringTable } from '@chilkat/react-native'

async function chilkatExample() {
  // Demonstrates the MailMan.FetchUidlSet method, which retrieves the messages whose UIDLs are
  // listed in a StringTable and appends them to an EmailBundle.  The arguments are the UIDL
  // StringTable, headersOnly, numBodyLines, and the EmailBundle.  The messages remain on the
  // server.

  const mailman = new MailMan();

  // Configure the POP3 server connection.
  mailman.mailHost = 'pop.example.com';
  mailman.mailPort = 995;
  mailman.popSsl = true;
  mailman.popUsername = 'user@example.com';
  mailman.popPassword = 'myPassword';

  // Build the set of UIDLs to fetch.
  const uidls = new StringTable();
  uidls.append('0000000123abcdef');
  uidls.append('0000000124abcdef');

  // Fetch the listed messages (full bodies) into a bundle.
  // headersOnly=false (fetch the entire message).
  // Note: numBodyLines only applies when headersOnly is true (it sets how many lines of the
  // body to include along with the headers).  When headersOnly is false, the entire message
  // is fetched and numBodyLines is ignored.
  const bundle = new EmailBundle();

  try {
    await mailman.fetchUidlSetAsync(uidls, false, 0, bundle);
  } catch {
    console.log(mailman.lastErrorText);
    return;
  }

  const n = bundle.messageCount;
  console.log(`Fetched ${n} messages.`);

  const email = new Email();
  for (let i = 0; i < n; i++) {
    bundle.emailAt(i, email);
    console.log(email.subject);
  }

  // Note: Explicitly connecting/authenticating is optional.  Chilkat MailMan automatically
  // connects and authenticates -- using the property settings above -- whenever a server
  // operation requires it.  Calling the explicit connect/authenticate methods can still be
  // helpful to determine whether a failure occurs while connecting or while authenticating.
}