>> directory index of "/srv/blog/" is forbidden

You have your website Content set up as Static Files (or not configured at all), but directory listings are disabled.

Also, check /var/log/nginx/.....error.log for exact error.

Do directory permissions allow access by web server (www-data user)? Try clicking "Fix permissions" on General tab.

Add a 443 port with SSL checkbox checked, and your certificate and key on SSL tab.

vsftpd support is only available as a part of Ajenti V right now (FTP access to the websites).

See if the PHP plugin got loaded in the Plugins page. Click on it to see what prevented it from loading.

Are you sure that this is an IMAP problem and mails are actually received and stored successfully by the SMTP server? (send some mail & see /var/log/exim4/....)

Check the logs in /var/log/mail*