Use of brackets with IPv6 addresses
[fe80::202:57ff:fec4:2334]The JavaMail API requires a combination of many host names or IP addresses with a port number, using the host:port number syntax . This extra colon can cause the port number to be read as part of an IPv6 address. Using brackets prevents your JavaMail implementation from processing the extra characters erroneously.
Related tasks
Configuring mail providers and sessions
Related reference
Mail providers and mail sessions