I agree with previous, particularly in relation to e-mail scanning programs; that is exactly what happens with Norton (and presumably others).
The secret is to keep an eye on your 'Sent Items' folder; e-mails will sit here between 'Outlook' informing you that they have been 'sent' and when the scanning is complete. If you have lots of outgoing e-mails sitting in this folder then you probably have a separate problem with your outgoing SMTP server or connection (?).