Using FastMail with Postbox

What you need to know

Postbox is a new email program for both Windows and Macintosh computers. Postbox shares much of the same underlying infrastructure from the Mozilla Thunderbird project.
Postbox fully supports IMAP and works well with FastMail.

Please be sure you have the latest build of PostBox (version 1.1.3 or later). Version 1.1.3 has the ability to auto-detect many domain settings and also supports the IMAPCOMPRESS extension utilized by FastMail.

The screen shots in this guide are taken from a computer running Windows Vista, but they are almost identical to the Macintosh version of Postbox.

Postbox offers a 30-day free trial available from:

Note: If you already know how to set up your client, and you already understand the information below, see this help page for the server information you need to set up your e-mail client. The Troubleshooting Issues section at the bottom of this page may be helpful if you have problems.

In order to use Postbox with FastMail, you'll need to enter the following information:

  • username - When you signed up for FastMail, you chose a username which is also your e-mail address. You must use the full username, including the name and the domain part, which is the part after the '@' symbol. For example, a user named John Doe might have chosen a username of "". Make sure that you specify your username in lowercase only.
  • password - When you signed up for FastMail, you chose a password to go along with your username. You will need the password to access your account. The password also keeps others from being able to access your e-mail. Your password is case sensitive, so be sure that you type it in correctly. "PASS123" is different to  "pass123". Often, users forget about the CapsLock button and mistype their password.
  • incoming mail server (IMAP or POP) - This is the server that you get your e-mail from. Internet Message Access Protocol (IMAP) and Post Office Protocol (POP) are retrieval methods used to move e-mail messages from the server to your e-mail client so that you can read your messages. POP access is not available for all service levels, please check the pricing table for details. Secure Sockets Layer (SSL) is required for your protection as well. SSL keeps people from reading your e-mail as it is transmitted between the e-mail server and your computer.
  • outgoing mail server (SMTP) - This is the server that sends your e-mail. Simple Mail Transfer Protocol (SMTP) is the method that your client uses to move e-mail messages from your client to the server so that it can send your messages. The FastMail SMTP server is not available for all service levels, please check the pricing table for details. If your service level does not allow use of the FastMail SMTP server, you must use the SMTP server provided by your Internet Service Provider (ISP).

    The FastMail SMTP server requires SMTP Authentication. This keeps people who are not users of the FastMail service from using the SMTP server to send spam messages on the Internet. SSL is required for the FastMail SMTP server. If you don't use the FastMail SMTP server, you may have different options or requirements. You will need to get that information from your ISP.

Incoming/Outgoing Server Setup

  1. First Time Startup
    After installing Postbox, you will be presented with the new start-up Setup window.
    Enter your name, your FastMail user name and password and press Next.

  2. Auto Configuration of Server Names
    Postbox (as of version 1.1.2) will detect most domains that are used by FastMail.
    The following page will be displayed.
    As long as the page displays in both incoming and outgoing servers, your initial setup is correct. Simply press Finish
    If those names are NOT displayed, click the Manual Setup... button to manually configure the correct values. The steps for manual configuration are listed in a section at the bottom of this guide.

  3. Adjust Special Folder Settings
    Your FastMail has many special folders as part of your mailbox (Sent Items, Trash, Junk Mail). PostBox will auto-configure the folder names, but we may want to fine-tune the Junk Mail behavior.

    Using the Menu, select Tools / Account Settings...

  4. Adjust Junk Mail Configuration
    Select Junk Settings from the list on the left.
    If you use a paid FastMail account, you already enjoy server-side junk mail filtering, you can choose to disable the junk-mail filtering within Postbox if you would prefer.

    You should still adjust the Junk Mail location within Postbox. Use the menu to select the Junk Mail folder in your FastMail account.

  5. Adjust Offline Settings
    Select Offline Settings from the list on the left.
    These settings will keep a copy of all your email data on your local hard disk (as well as on FastMail servers).

    Enable the Make the messages in My Inbox available checkbox.
    You can also select other folders that will be made available offline (great when you need to read your email on a long airplane flight).

    When complete, you can press the OK button to save all your Account Settings changes.

    Postbox is now setup correctly to access your FastMail account!

    Your folder list in Postbox should appear similar to the following:

Manual Server Name Configuration

This section only needs to be completed if PostBox could not auto-detect your settings. Most users will not need to perform these steps.

  1. Fix Server Names
    If PostBox could not auto-detect the servers, you must manually alter these values. Be sure that Server Settings is selected on the left.
      Adjust the Server Name to be
      Ensure your User Name contains your complete FastMail username
      Choose SSL as your secure connection type
      The Port number should be set to 993

    The result will look similar to the image below:

  2. Adjust Outgoing Server
    Next click on the Outgoing Server (SMTP) selection on the left.
    Ensure your new account is selected and press the Edit... button.

    A new page will appear.
      Adjust the Server Name to be
      Ensure your User Name contains your complete FastMail username
      Choose SMTP-over-SSL as your secure connection type
      The Port number should be set to 465
    Press OK when you are finished adjusting values.

    Press OK again to save all of your settings.

  3. Enter Password for the First Time
    After pressing OK, Postbox will attempt its first connection to your account.
    A password page will be presented. Enter your account password and press OK.

  4. Adjust Sent Items Location
    Select Copies & Folders from the list on the left.
    Choose Other under the Place a copy in... selection.
    Using the menus, select your Sent Items folder from your account.

    After selection, the Copies & Folders page should appear similar to below:

    You should now adjust the other settings

Optional: Sync your Offline Database

If you have are planning on being offline and have a large amount of email stored in your FastMail account, you may want to perform the first sync now.

Using the menu, choose File / Offline / Download, Sync Now... The following window will appear. Be sure to put a Checkbox for the Mail messages.

Press the OK button and Postbox will download all your email to an offline database on your local hard drive.

Special Notes

As of Release 1.1.2, Postbox now has native built-in support for the FastMail compression technique.

Fixing the INBOX/Trash Bug

This has been resolved as of version 1.1.3 of PostBox. Once you have performed the upgrade, you should be able to remove the extra Trash folder and restart PostBox.

Last modified on: Thu Mar 18 18:00:00 UTC 2010