MailZip Pro Description:

MailZip Pro is the most powerful and multifunctional Microsoft Outlook add-in for managing of attached files. Main features of MailZip Pro:
MailZip Pro automatically archives attachments in outgoing messages, unpacks archives in incoming messages and works with password-protected archives
MailZip Pro opens or saves attached files in a selected folder on a local or network drive
MailZip Pro opens or saves hidden attachments
Microsoft Outlook hides same files like picture in mail message. MailZip Pro allows opening or saving hidden attachments like background pictures Automatic packing of big-sized files in outgoing messages can save you time and money thanks to traffic economy. In some cases, for example, when sending text documents, packing into a ZIP-archive can reduce the size of them in many times. That allows to reduce the time of sending a message and traffic consumption.

By default, Microsoft Outlook blocks those file types that can be potentially dangerous and can cause a lot of problems if you want to send such a file to the recipient. But if this file is ZIP-archived, the recipient will surely have access to it. At the same time, the use of password-protected archives allows you to be sure that packed files are going to be viewed only by the person whom they are destined to.