One of the most common ways of transmitting computer viruses is through file attachments. To help protect you and your recipients against computer viruses, Outlook blocks the sending and receiving of certain types of files (such as .exe and certain database files) as attachments.

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Documents, spreadsheets, PDF files, and other types of files can vary greatly in size. There are several methods you can use to keep the size of your email messages and attachments small when sending these files. For more information specific to reducing picture files, see the section.

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