test logo
Login Sign Up
back to the blog

How to Sync Contacts with CardDAV on Mailbux (iPhone, Android, Mac, PC)

How to Sync Contacts with CardDAV on Mailbux (iPhone, Android, Mac, PC)

Keeping your contacts synchronized across every device you own sounds like it should be simple — but if you have ever lost a phone and realized your address book vanished with it, you know the reality is different. CardDAV solves this problem at the protocol level, and Mailbux supports it natively with every account.

This guide walks you through setting up CardDAV contacts sync on iPhone, Android, Mac, PC, and popular desktop email clients — so your contacts live on the server and stay perfectly in sync everywhere.

What Is CardDAV?

CardDAV is an open internet standard (RFC 6352) for synchronizing contact data between a server and your devices. Think of it as IMAP for your address book. Instead of contacts being trapped on a single phone or inside a single app, CardDAV stores them on your mail server and pushes changes to every connected device in real time.

When you add a new contact on your iPhone, it appears on your Mac, your Android tablet, and your webmail — automatically. Edit a phone number on your laptop, and the update propagates everywhere. Delete a duplicate on one device, and it disappears from all of them.

CardDAV uses the vCard format (the same .vcf files you may have shared before) and communicates over HTTPS, so your contact data is always encrypted in transit.

Why Sync Contacts with Mailbux?

If you are already using Mailbux for your custom domain email, your CardDAV server is ready and waiting. Here is why that matters:

  • One address book everywhere — Phone, tablet, laptop, desktop, webmail. Every device sees the same contacts.
  • No more lost contacts — Contacts live on the server. Lose a device? Log in on the replacement and everything is already there.
  • No third-party dependency — You are not relying on Google Contacts or iCloud. Your contacts sit on infrastructure you control, under your own domain.
  • Privacy — Your address book is not being mined for advertising data. It stays between you and your Mailbux server.
  • Works with standard apps — No proprietary apps required. iPhone Contacts, Android DAVx5, macOS Contacts, Thunderbird — they all speak CardDAV.

Mailbux CardDAV Server Details

Before we dive into device-specific instructions, here are the settings you will need:

Setting Value
CardDAV Servermy.mailbux.com
URLhttps://my.mailbux.com/dav/contacts/
UsernameYour full email address (e.g., you@yourdomain.com)
PasswordYour Mailbux email password
EncryptionSSL/TLS (always enabled)

Use the same credentials you use to log in to your Mailbux email. No separate account or API key is needed.

Setup Guide: iPhone and iPad

iOS has native CardDAV support built into the Contacts app. No third-party apps are needed.

  1. Open Settings on your iPhone or iPad
  2. Tap Contacts (or Contacts > Accounts on newer iOS versions)
  3. Tap Accounts > Add Account
  4. Select Other at the bottom of the list
  5. Under Contacts, tap Add CardDAV Account
  6. Enter the following:
    • Server: my.mailbux.com
    • User Name: Your full email address
    • Password: Your email password
    • Description: Mailbux Contacts (or whatever you prefer)
  7. Tap Next — iOS will verify the connection and start syncing

Once connected, open the Contacts app, tap Groups, and make sure your Mailbux address book is checked. New contacts you create will sync to the server automatically.

Setup Guide: Android

Android does not include a built-in CardDAV client, but the free and open-source DAVx5 app handles it perfectly.

  1. Install DAVx5 from Google Play or F-Droid
  2. Open DAVx5 and tap the + button to add an account
  3. Select Login with URL and user name
  4. Enter:
    • Base URL: https://my.mailbux.com/dav/
    • User name: Your full email address
    • Password: Your email password
  5. Tap Login — DAVx5 will detect your address books (and calendars, if any)
  6. Check the address books you want to sync and tap the sync icon

DAVx5 runs in the background and keeps your Android contacts app synchronized with Mailbux. It also supports CalDAV for calendar sync if you need it.

Setup Guide: macOS

The built-in macOS Contacts app supports CardDAV natively.

  1. Open System Settings (or System Preferences on older macOS)
  2. Go to Internet Accounts
  3. Click Add Other Account at the bottom
  4. Select CardDAV account
  5. Choose Manual for the account type
  6. Enter:
    • User Name: Your full email address
    • Password: Your email password
    • Server Address: my.mailbux.com
  7. Click Sign In

Your Mailbux contacts will now appear in the macOS Contacts app. Any changes you make sync back to the server and out to all your other devices.

Setup Guide: Thunderbird (Windows, Mac, Linux)

Thunderbird supports CardDAV contacts natively starting from version 102. For older versions, you will need the TbSync add-on with the CardDAV provider.

Thunderbird 102 and newer

  1. Open Thunderbird and go to the Address Book (click the address book icon in the toolbar)
  2. Click New Address Book > Add CardDAV Address Book
  3. Enter your full Mailbux email address and click Continue
  4. If auto-discovery does not find the server, enter the URL manually: https://my.mailbux.com/dav/contacts/
  5. Enter your password when prompted
  6. Select the address books to sync and click Continue

Older Thunderbird versions (TbSync)

  1. Install the TbSync add-on and the Provider for CalDAV & CardDAV add-on
  2. Go to Tools > TbSync Account Manager
  3. Click Add New Account > CalDAV & CardDAV
  4. Select Manual Configuration
  5. Enter https://my.mailbux.com/dav/contacts/ as the CardDAV server URL
  6. Enter your full email address and password
  7. Enable sync for the discovered address books

Setup Guide: Outlook (Windows)

Microsoft Outlook does not support CardDAV natively. You have two options:

  • Option A: Use a CardDAV plugin. Plugins like CalDAV Synchronizer (free, open-source) add CardDAV support to Outlook. Install the plugin, add a new sync profile with the server URL https://my.mailbux.com/dav/contacts/, your email, and password.
  • Option B: Use Mailbux webmail. Access your contacts directly through the Mailbux webmail interface at my.mailbux.com without installing anything. Your contacts are always available in the browser.

Migrating Existing Contacts to Mailbux

If you are switching from another email provider or from Google/iCloud contacts, migrating is straightforward:

  1. Export from your old provider: Most services let you export contacts as a .vcf (vCard) file. In Google Contacts, go to Export > vCard. In iCloud, select all contacts and choose Export vCard. In Outlook, export as CSV and convert to vCard using a free online tool.
  2. Import to Mailbux: Log into your Mailbux webmail at my.mailbux.com, navigate to Contacts, and use the Import function to upload your .vcf file.
  3. Verify sync: Once imported, open the Contacts app on any device where you have configured CardDAV. Your migrated contacts should appear within a few minutes.

You can also import vCard files directly through Thunderbird or any other CardDAV-capable client — just drag the .vcf file into the synced address book.

Troubleshooting

Contacts not syncing

  • Verify you are using your full email address as the username, not just the local part
  • Make sure the server URL is exactly https://my.mailbux.com/dav/contacts/ (with the trailing slash)
  • On Android, check that DAVx5 has battery optimization disabled — Android may kill background sync
  • On iOS, go to Settings > Contacts > Accounts and verify the CardDAV account shows as connected

Authentication errors

  • Double-check your password. Try logging into Mailbux webmail at my.mailbux.com with the same credentials to confirm they work
  • Make sure you are not using an app-specific password if you do not need one — Mailbux uses your regular email password for CardDAV

Duplicate contacts appearing

  • This usually happens when contacts exist both locally on your device and on the server. On iOS, disable the On My iPhone account in Contacts > Groups. On Android, check DAVx5 sync settings to avoid merging with local contacts.
  • Most email clients can detect and merge duplicates — use the built-in duplicate detection if available

Slow initial sync

  • The first sync may take a few minutes if you have a large address book. Subsequent syncs are incremental and near-instant.

Final Thoughts

CardDAV contacts sync is one of those features that works quietly in the background once configured — and you only appreciate it when you realize you never have to manually transfer contacts between devices again. With Mailbux, your address book lives alongside your email on infrastructure you control, accessible from every device and platform.

Set it up once on each device, and your contacts stay synchronized forever.

New to Mailbux? Create your free account — 15 GB storage, custom domain, and built-in CardDAV and CalDAV support included with every plan.