Please send the sample in a password-protected zip folder to virus@avast.com with undetected malware in subject and the password mentioned in the email body.
Don’t wrap email addresses in the URL tag as a) treats it as a web link, b) it won’t open your email client, if that was the intention. I have modded the quote so it doesn’t show as a web link, but to show the URL tags.
Just plain old virus@avast.com or virus(at)avast(dot)com is probably better.