True or False: Port number 389 is used for unsecured LDAP connections in Mimecast.

Port number 389 is indeed used for unsecured LDAP (Lightweight Directory Access Protocol) connections. In the context of Mimecast, this port facilitates communication with directory services that do not employ encryption, allowing for straightforward access to directory data. It is a commonly accepted standard for LDAP traffic that is not secured by protocols such as SSL or TLS.

On the other hand, secure LDAP connections utilize port 636, which employs secure socket layer (SSL) for encrypting data transferred between clients and servers. Therefore, the distinction between these two ports is crucial for understanding how data security is implemented in directory services.

The other options correctly highlight alternative uses or definitions but do not pertain specifically to unsecured LDAP connections associated with port 389. Therefore, the assertion that port number 389 corresponds to unsecured LDAP connections is valid.