Error 534 is a 5xx
error code, which means there has been an issue with the server while attempting to send the email.
This could be due to an issue with the server or configuration, or it could mean that the email address you are trying to send to is incorrect or inactive.
When attempting to connect to a web server that requires a secure connection, a 534 error may occur if the client (such as an FTP client) does not have
SSL/ TLS enabled. This is because the server will not accept unsecured communication, and the client must use a secure channel in order to access the server.
When a user attempts to establish a connection without Secure Socket Layer (SSL) encryption, they may experience an error that terminates their connection abruptly and without any indication of how the issue can be corrected.
This error can be unexpected and frustrating, as it does not give users the opportunity to try other means of connecting.
SSL (Secure Sockets Layer) is a security protocol designed to ensure that all data passing between a web server and its users is encrypted, and that only authorized users are able to access the server.
If a user is attempting to connect to an SSL-protected server without using an SSL-encrypted connection, they will likely receive a 534 error until they establish an SSL connection through their FTP client.
It is always important to use an SSL-encrypted connection when accessing a web server, as it provides an added layer of security.