Can't log in using an email address with + in its name

[system]

I have been a registered user of Avast for years, under this same email address.

I assure you, my email address does indeed have a +, and I receive emails there all the time. While I can log in on the web site with that address, I cannot sign in on the Avast tool.

Specifically, my email address is something+something@gmail.com

[Pondus]

same problem with avast forum log in, i have underscore _ in my address and often get a “not valid email address” message