Does Spamcc support checking mails of Hotmail?
Yes, Hotmail now supports POP3. Please visit here for details.

How should mail filter and group just modified come into effect immediately?
Click the 'Tools' menu, and select 'Apply Filters'. New version Spamcc can automatically do it.

I am trying out Spamcc. I'm getting a lot of spam with PDF files in attachments. I tried setting a filter - If field attachment contains *.pdf move to spam folder. But it doesn't seem to work - do you know what I am doing wrong?
The attachment filter does not support wildcard, so you can input pdf instead of *.pdf in setting dialog.

How can I set up the Gmail account in Spamcc?
To configure Gmail in Spamcc as follow:
1. Enable POP in your Gmail account
2. Open Spamcc
3. Click the 'Tools' menu, and select 'Accounts...'
Now in Accounts dialog, you can add a new account named gmail, choose POP3 in 'Server type', enter pop.gmail.com in 'Server address', enter your full Gmail email address in 'Account name', and enter password. Then in 'Advance' tab, check the box next to 'This server requires a secure connection'. Now you can receive messages from Gmail.

Why does Spamcc Pro crash in Windows Vista or Windows 7?
Please try to change Data Execution Prevention settings for Spamcc Pro, visit here for details.