What are the dangers of email attachments?

Updated February 21, 2017

Almost everyone who has access to the Internet also has an e-mail address. Those who use e-mail have the option of adding e-mail attachments to their messages. These messages can contain any file that the sender wishes, provided that the file is within the size limits of the email provider. This means that e-mail is highly effective at transferring information from place to place and person to person. However, using e-mail attachments is not without its dangers.

Most common risk

The most common problem with e-mail attachments is the risk of viruses, Trojans and worms. These programs are disguised within the attachments and can cause numerous problems (for example, deleted files) for the person who downloads the attachment. Viruses, Trojans and worms can self-propagate once active on a machine and are difficult to get rid of.

Loss/corruption of data

A virus, Trojan or worm that comes in as an e-mail attachment can be a program that is designed specifically to destroy or to corrupt files that are on the user's machine. In some instances, the program may wipe the user's entire hard drive. Corrupted files can cause significant data losses and problems with the way that the computer is able to operate.

Loss of personal information

Some programs that are sent via e-mail attachment are created to steal user information. Some of these programs steal information about what websites have been visited, for instance, or they steal data that may be entered on websites (including bank account numbers and National Insurance numbers). This data is then sent back to the computer of the individual who sent the email attachment. In some cases the data stolen results only in annoyance (for example, increased pop-ups for a particular store while browsing the Internet), but it also can result in complete identity theft or financial loss.


Once an e-mail attachment is sent, a computer user cannot control to whom recipients forward the attachment. If the information is confidential, then sending the data as an attachment runs the risk of releasing data that should not be released to a third party.

How to avoid problems

In order to avoid the potential dangers of e-mail attachments, it is best to run a scan on all e-mail attachments received. This scan can tell you if the file attached is a potential threat. In addition, don't open any attachments with file extensions you don't recognise, and verify that the sender is legitimate and that they have sent you a file to be opened.

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About the Author

Wanda Thibodeaux is a freelance writer and editor based in Eagan, Minn. She has been published in both print and Web publications and has written on everything from fly fishing to parenting. She currently works through her business website,, which functions globally and welcomes new clients.