Overview
If Mailbird Next cannot reach your email server while you are adding an account, the problem is usually related to the server address, port, local network configuration, DNS, or a proxy running on your device.
This article covers common setup errors such as server not found, hostname not found, connection refused, localhost connection refused, address unavailable, and similar network-level failures.
What to check first
Check the incoming and outgoing server names carefully. A small typo in the server address is enough to prevent Mailbird from connecting.
Verify the port numbers and encryption method. Make sure the ports match the protocol and security method your provider expects.
Confirm that the server actually exists for your provider. If you entered a custom server manually, compare it against your provider's official documentation.
Make sure your internet connection is stable. If possible, retry on a different network.
Common connection errors
1. Hostname not found / DNS resolution failure
This usually means the server name cannot be resolved to an address.
Check for spelling mistakes in the server name.
Remove extra spaces or accidental characters.
Confirm you are using the correct mail server for your provider.
If you are on a restricted network, try another connection or disable VPN or proxy temporarily.
2. Connection refused by the remote server
This usually means Mailbird reached the server, but the server rejected the connection.
Double-check the port number and security setting.
Confirm you selected the right protocol: IMAP, POP3, SMTP, Exchange, or Outlook.
Some providers block certain ports or require authentication before SMTP can be used.
A firewall or provider-side restriction can also cause this.
3. Connection refused on localhost
If the error references 127.0.0.1 or localhost, a local proxy or mail-routing service on your computer may not be running correctly.
Check whether you intentionally use a local proxy, security app, or network utility.
Restart the related local service if you know what it is.
If you do not expect Mailbird to use localhost at all, review any proxy settings or security tools installed on your device.
4. Address unavailable / local network configuration issue
This can happen when the local network interface or a custom binding is unavailable.
Restart Mailbird and your computer.
Disconnect and reconnect to your network.
Disable VPN, proxy, or advanced network routing tools temporarily and try again.
5. Exchange server cannot be resolved
If you are adding an Exchange account and the server cannot be found:
Make sure you are using the correct Exchange server or EWS URL.
If your organization normally relies on autodiscover, try that option first.
If you are unsure which server to use, contact your IT administrator.
When to try manual setup
If automatic detection fails, manual setup can help you confirm whether the issue is with autodiscovery or with the server details themselves. Be sure to enter the exact incoming and outgoing settings provided by your email provider.
Still need help?
If the issue continues, contact our support team and include the exact error message shown in Mailbird, the server names and port numbers you entered, whether you are using IMAP, POP3, Exchange, or Outlook, and whether a VPN, proxy, firewall, or antivirus tool is active.