Thank you for your post. However, McAfee Japan Corporate Support Community is intended for the convenience of Japanese-speaking customers. If you are an English-speaking customer, please visit other McAfee Communities. Thank you.
This community page solely in Japanese. Therefore, if you want to raise a question in English, please go to the following Email and Web Security page. Appropriate people can answer to your question:
(McAfee Community - Email and Web Security)
Answering to your question, McAfee Web Gateway is specialized to scan web-related protocol such as http/https/icap/ftp, is Not scanning smtp protocol. If you want a device for anti-virus/ anti-spam through smtp, you may want to implement McAfee Email Gateway or McAfee Email and Web Security (Important note is that the support period of McAfee Email and Web Gateway would be limited until 2017, therefore choosing EWS is not so good at this point).
The Web Gateway product is the McAfee Web related product moving forward.
Specifically Web Gateway offers a lot more granual filtering, ssl scanning, more methods for authentication, enhanced logging capabilities, and many more.