Unencrypted passwords are blocked

[Looeallotments]

I am annoyed that it looks like I cannot use the forum and will have to embed a rival product.
Registration to the forum is blocked by Bitdefender with the message

Online Threat Prevention
An attempt to send your password unencrypted was about to occur on mysite.nabble.com. We blocked the connection to stop your private data from being exposed and tampered with.

I know how to add an exception, but most of our potential users do not.
How do I get round this?

[GregChapman]

It sounds as if Bitdefender may complaining that Nabble does not run under https://.
See the Topics at:
http://support.nabble.com/HTTPS-Protocol-tp7600829.html
and
http://support.nabble.com/Https-Protocol-Request-tp7600969.html