The line in the logs, "[Att-Blk] Got Attachment Blocking Host Info for ...." means that the message had an attachment, and IMail's Queue Manager checked it against the domain's Attachment Blocking settings, whether enabled or not.
If Attachment Blocking actually did something with the attachment, the log lines would look like this:
(0cdf000000010002) [Att-Blk] Got Attachment Blocking Host Info for mail.sql.domain
(0cdf000000010002) [Att-Blk] Attachment blocked (Type = Filename, Content = Spam.rar, Action = Strip)
(0cdf000000010002) [Att-Blk] One or more attachments were blocked in C:\Program Files\Ipswitch\IMail\spool\D0cdf000000010002.SMD