Email clients

Set up a ZoPanel mailbox in Outlook, Thunderbird, Apple Mail, the Gmail app or any IMAP/POP3 client, with the exact servers, ports and encryption, and fix common errors.

Updated Oct 9, 2026 · 8 min read

Every mailbox on a ZoPanel server works with any standard mail app over IMAP or POP3 for incoming mail and SMTP for sending. This page lists the exact settings, explains which apps can configure themselves, and walks through Outlook, Thunderbird, Apple Mail and the Gmail app. To create mailboxes first, see Email.

Before you start

You need:

• The mailbox address and its password. The password is shown once when the mailbox is created. If it is lost, change it with the key icon in the mailbox list on Email → the domain.
• The server name. Use the mail hostname that was set when the mail server was installed, such as mail.example.com. Automatic setup and the iPhone/Mac profile use this name.
• The domain's DNS records published, so that other servers can deliver mail to you.

Important: the mail services use the panel's certificate (Settings → Panel domain & SSL). That certificate names the panel domain and, when it points to the server, the mail hostname, so mail apps connecting to either name see no warning. Until the panel has a Let's Encrypt certificate, every mail app shows a certificate warning.

There are no app passwords. Mail apps sign in with the mailbox password itself, and two-factor authentication applies to panel logins only, not to mailboxes.

Server settings

The username is always the full email address, for example anna@example.com. Sign-in always requires encryption, and the authentication method is a normal password (not "Secure Password Authentication", NTLM or OAuth).

• IMAP keeps mail on the server and syncs folders (Inbox, Sent, Drafts, Junk, Trash) across all your devices. Use it unless you have a reason not to.
• POP3 downloads the inbox to one device. Other folders are not synced.
• Outgoing mail always needs a login (My outgoing server requires authentication, using the same username and password). Port 25 is for server-to-server delivery and is not for mail apps.
• A message can be at most 50 MB, including attachments. Attachments grow by about a third when they are encoded, so keep attachments under about 35 MB.

The domain page on Email shows these values in the Email client settings card: IMAP (SSL), SMTP (STARTTLS / SSL), POP3 (SSL) and Calendars & contacts. The card shows the mail hostname as the server name.

Automatic setup

ZoPanel answers the lookups that mail apps make when you type an address:

The first two answers are served by the domain's website. They only work when the website for example.com is hosted on this server and the domain points to it. Every website on the server serves them once the mail server is installed. Outlook does not always use this lookup; if it cannot find the settings, enter them by hand.

Outlook

Outlook for Windows (classic)

1. Choose File → Add Account.
2. Enter the email address, open Advanced options, tick Let me set up my account manually and click Connect.
3. Choose IMAP.
4. Incoming mail: server = mail hostname, port 993, encryption method SSL/TLS.
5. Outgoing mail: server = mail hostname, port 465, encryption method SSL/TLS.
6. Leave Require logon using Secure Password Authentication (SPA) off in both sections, click Next and enter the mailbox password.

New Outlook for Windows

1. Open Settings → Accounts → Email accounts → Add account.
2. Enter the email address and continue. If Outlook does not find the settings, choose IMAP.
3. Enter the password, open the advanced settings and fill in the IMAP server (port 993, SSL/TLS) and the SMTP server (port 465, SSL/TLS), with the full address as the username for both.

Note: the new Outlook synchronises non-Microsoft accounts through Microsoft's cloud, so the connections to your server come from Microsoft's addresses, not from your computer. Keep this in mind if you use country blocking on all ports.

Outlook for Mac

1. Choose Outlook → Settings → Accounts, click + and New Account.
2. Enter the email address. If Outlook asks for the provider, choose IMAP/POP.
3. Choose type IMAP, then enter the username (full address), password, the incoming server with port 993 and SSL on, and the outgoing server with port 465 and SSL on.
4. Click Add Account.

Thunderbird

1. Open the menu ≡ → New Account → Email (or Account Settings → Account Actions → Add Mail Account).
2. Enter your name, the email address and the password, then click Continue.
3. If the domain's website is on this server, Thunderbird finds the settings by itself. Choose IMAP and click Done.
4. Otherwise click Configure manually and enter the values from Server settings, with Authentication set to Normal password.

Apple Mail (iPhone, iPad and Mac)

With the configuration profile

1. In the panel, open Email → the domain, and click the phone icon iPhone / Mac profile (sets up this mailbox) on the mailbox's row. You must be signed in to the panel in that browser, so on an iPhone open the panel in Safari, or download the file on a Mac and send it to the phone with AirDrop.
2. On iPhone or iPad, open Settings, tap Profile Downloaded and then Install. On a Mac, open System Settings and install it from Profiles (type "Profiles" in the search field).
3. Enter the mailbox password when asked. The password is not stored in the file.

The profile is not signed, so iOS and macOS show it as unverified. That is expected. Removing the profile removes the account.

Manually

1. On iPhone or iPad, open Settings → Mail → Accounts → Add Account → Other → Add Mail Account (on recent iOS versions, Mail is under Settings → Apps). On a Mac, open Mail → Add Account → Other Mail Account.
2. Enter the name, email address and password.
3. Choose IMAP and enter the mail hostname as both Incoming Mail Server and Outgoing Mail Server, with the full address as the username for both.
4. Save. To check the ports, open the account's Advanced settings: IMAP 993 with SSL, and under Outgoing Mail Server (SMTP) port 465 with SSL.

Gmail app on Android

1. Open the Gmail app, tap your profile picture and choose Add another account → Other.
2. Enter the email address and tap Manual setup.
3. Choose Personal (IMAP) and enter the password.
4. Incoming server settings: username = full address, server = mail hostname. If asked, port 993 with SSL/TLS.
5. Outgoing server settings: keep Require sign-in on, username = full address, SMTP server = mail hostname. If asked, port 465 with SSL/TLS.
6. Choose the sync options and finish.

Other Android mail apps use the same values.

Sending from websites and scripts

Applications send mail through this server with PHP mail() or an SMTP login on port 587 (STARTTLS) or 465 (SSL/TLS) with a mailbox address and password. Direct connections from websites to other servers on port 25 are blocked, and every account has an hourly sending limit. See Mail rules and limits.

Troubleshooting

Authentication failed / wrong password

• The username must be the full address, not just the part before @.
• Reset the password with the key icon on the mailbox's row and enter the new one on every device. Devices that keep trying the old password count as failed logins.
• After 5 failed logins within 10 minutes, Fail2ban bans the client's IP for 1 hour (IMAP, POP3 and SMTP alike). An administrator can lift the ban with Unban on the Security page and can add the office IP under Trusted addresses (fail2ban).
• Mailboxes of a suspended hosting account cannot sign in until the account is unsuspended.

Certificate warning (name does not match, or untrusted)

• Before Settings → Panel domain & SSL is set up, the server uses a self-signed certificate. Ask the administrator to set it up.
• If the warning says the name does not match, the app connects with a name that is not on the panel certificate. Use the mail hostname (or the panel domain) as the server name. If the mail hostname itself is refused, it did not point to the server when the certificate was issued: ask the administrator to click Issue certificate again in Settings → Panel domain & SSL once it does.

Cannot connect at all (timeout)

• Check that the mail hostname resolves to the server.
• Some office, hotel and mobile networks block mail ports. Try another network, or IMAP 993 and SMTP 465 instead of 143 and 587.
• If the administrator blocks countries on all ports, connections from those countries are dropped. See Country blocking.

Sending fails: "Sender address rejected: not owned by user"

You can only send as the mailbox you signed in with. Forwarder and mailing list addresses cannot be used as the From address over SMTP. Create a mailbox for the address you want to send from.

Sending fails: "Sending limit reached (N recipients per hour), try again later"

The hosting account reached its hourly limit. Wait until older messages leave the one-hour window, or ask the administrator about the limit. If you did not send that much mail, a website on the account may be sending spam.

Mail is accepted but never arrives at Gmail, Outlook.com and others

The administrator sees a warning on Email when the VPS provider blocks outgoing port 25. Until the provider opens it, or an Outgoing mail relay (smarthost) is configured, mail to other servers stays in the queue. Run Mail delivery check on the domain to find missing DNS records. See Email.

Mailbox full

When a mailbox reaches its Quota (MB) (with a 10% grace margin), new messages are refused and senders get a bounce. Delete old mail and empty Trash and Junk, or raise the quota with the key icon. The Usage column shows how much space is used.

Related

• Email
• Mail rules and limits
• Webmail, calendars and contacts
• Panel settings
• Country blocking
• Thunderbird: automatic account configuration