Many forum and wiki administrators dislike DEAs because they obfuscate the identity of the members and make maintaining member control difficult. As an example, trolls, vandals and other users that may have been banned may use throwaway e-mail addresses to get around attempts to ban them. Using a DEA provider only makes this easier; the same convenience with which a person may create a DEA to filter spam also applies to trolls. For this reason, most forum programs have functionality to make it easier to ban DEAs. As a result, forum, wiki administrators, blog owners, and indeed any public site requiring user names may have a compelling reason to ban DEAs. Site operators that expect to generate revenue from the sales of gathered user e-mail addresses may choose to ban DEAs as well due to the low market value of such addresses.
As a counterbalance to the risks of asking a user to give a "permanent" e-mail address in a publicly accessible site, administrators have the option to prevent, or give the option for hiding, the publication of users' email addresses. An "e-mail this user" script can be used to allow communication with the user without the sender knowing their e-mail address. This provides some minimal protection of users from spam and allows them to use real email addresses, which may make a ban on DEAs easier for users to accept. The problem is when the website itself is hacked, and the real addresses and other personal information is stolen, or when the website changes owners and email policies changed without notice to the user, or if the website intended to spam the user from the beginning.