IMAP and SMTP errors: what they mean and how to fix them
In short
“The server rejected your credentials” almost always means a wrong password or a missing app password; “Could not reach the server” points to the wrong server, port or network; TLS certificate problems come from the server. Check the values in the server table and try again with “Test connection”.
What does “The server rejected your credentials” mean?#
The server responded, but rejected your email or password (“The mail server (IMAP) rejected the sign-in: check your email address and password.”). The most common causes:
- a wrong password, or one recently changed in webmail;
- the provider requires an app password (Gmail, iCloud, Yahoo, Libero with 2-step verification): see App password rejected;
- for Outlook, Hotmail and Live the password is no longer accepted: use Sign in with Microsoft;
- for GMX and WEB.DE, IMAP access isn’t enabled in webmail.
When a mailbox that’s already set up stops accepting the password, the sidebar shows the status Password needs updating.
What does “Could not reach the server” mean?#
Mailamber can’t connect to the address and port you entered (“Could not reach the server. Check host and port.”). Check:
- the server name, with no typos (for Libero it’s
imapmail.libero.it, notimap.libero.it); - the port: 993 for IMAP, 465 or 587 for SMTP, with the right security (TLS for 993/465, STARTTLS for 587);
- your connection: VPNs, corporate firewalls or antivirus software that filters email can block ports 993, 465 and 587.
The correct values are in the server table.
What does “Problem with the server TLS certificate” mean?#
The server presented a certificate that’s invalid, expired or issued to a different name (“Problem with the server TLS certificate.”). Mailamber refuses the connection to protect your password. Make sure you typed the server name exactly as your provider gives it (hosting companies often use a name that differs from your domain, such as mail.provider.it). If the problem persists, report it to your provider.
Why can I receive but not send?#
The problem is almost always SMTP. Check the outgoing server and port, and try Test SMTP. The most common sending errors are:
- “The SMTP server rejected your credentials.”: the SMTP password is different from the IMAP one, or missing;
- “The server rejected the message.”: the provider rejected the message, for example because of an invalid recipient, an attachment that’s too large or exceeded sending limits;
- “The attachments exceed the maximum allowed size.”: reduce the attachments (25 MB in total at most).
The unsent message stays in the Outbox queue, ready for Retry.
Automatic detection can’t find the servers: what do I do?#
If you see “We couldn't detect the settings. Enter them manually below.”, enter the servers manually in Server settings: you’ll find them in your provider’s guide or in our table. You only need to do it once.
Still stuck: how do I ask for help?#
Write to us with your provider, the exact message you see, and whether it happens on your PC, phone or both. Never send us your mailbox password: we don’t need it.