What OS?
What email client do you use?
What exact provider is saying “waiting…”?

The help section also says:

Version 4.5 of avast! Antivirus brings a new method of email protection. It does not require any manual settings (additionally, the accounts in the email programs are preserved). So, if you use avast! 4.5 or higher and your operating system is Windows NT, 2000, XP or 2003, you can safely ignore the following paragraphs - your email will be protected automatically, just as it is in MS Outlook or MS Exchange clients.