Stop at the warning and identify the connection
A certificate name warning means the identity presented by the mail server has not matched the name the app expected. Do not accept an exception, disable certificate checks or switch off TLS to make the warning disappear.
Note whether the warning appeared while receiving mail through IMAP or POP, or sending through authenticated SMTP submission. Record the exact server name, port, security mode, warning text and time. Keep passwords and reset links out of screenshots and ordinary support messages. A working webmail session does not prove that a separate IMAP or submission connection has the right certificate.
Compare the configured name with the real mailbox service
Use the mail settings supplied through the trusted account or by the operator of the mailbox included in your accepted service. Compare the app’s incoming and outgoing server names separately. The domain after your email address, your website name and the MX record are not automatically the names to enter for IMAP or SMTP submission. A mail app’s automatic setup can also propose a different host from the one your provider currently supports.
If the app is using an old or mistyped name, correct only that endpoint to the documented hostname, port and encrypted mode. Preserve the previous settings so you can reverse the change. Do not replace a known service hostname with an unfamiliar name merely because it appears on the warning’s certificate. If you cannot establish the right endpoint independently, ask the mail operator before entering your password again.
Understand which certificate should be presented
The certificate must be valid for the mail-server identity the client verifies, and its trust and validity checks must also pass. A certificate for www.example.com does not by itself cover mail.example.com; a valid website padlock does not prove the mail service is configured correctly. Similarly, an IMAP success does not establish that the SMTP submission endpoint has the right certificate.
DirectAdmin can use a server-hostname certificate for its Exim and Dovecot mail services, and an operator can configure per-domain mail certificates using SNI. The actual certificate depends on the server and service configuration. Customers should use the documented endpoint for their mailbox, not assume that every custom mail. hostname is covered.
Ask the operator when the documented endpoint still fails
If the app uses the confirmed hostname and encrypted mode but still receives a mismatched, expired or untrusted certificate, stop changing client settings and report the evidence to the mail operator. Include the affected incoming or outgoing endpoint, port, time, app and exact warning, without sending a password. The operator can inspect the certificate actually served by the relevant mail process, the configured server hostname, renewal state and any mail SNI mapping. An administrator may need to correct deployment; a customer cannot prove a server-side fix by accepting a local exception.
If a warning starts unexpectedly on several devices, treat the changed certificate as a new fact to verify with the operator. Avoid trying repeated credentials until the server identity is clear.
Verify both directions after correction
Reconnect using the confirmed encrypted settings with certificate verification enabled. Confirm that the warning has gone without an exception. Send a non-sensitive test message to an external address you control and verify it arrives; reply and confirm that the mailbox receives it through the client. If one direction still fails, record which endpoint failed and use the corresponding sending or receiving guide.
Keep existing messages and account data intact while testing. Do not delete and recreate a POP account without first checking what mail is stored only on that device.
Common questions
Should I click “trust this certificate”? Not as a workaround for an unexplained name mismatch. Verify the correct endpoint and have the operator correct the presented certificate where needed.
Does changing my password repair a certificate mismatch? No. A password authenticates the mailbox after the connection is established; it does not make a different server identity valid.
Can I use my website certificate? Only if the mail service actually presents a valid certificate covering the mail hostname. Website and mail certificates can be deployed separately.
Is the MX record my outgoing SMTP server? Not necessarily. MX identifies where incoming domain mail is delivered; the provider supplies the client submission endpoint.
Sources and technical references
Related guides
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