Although the Internal Revenue Service denies that it actually does this, of course. Documents obtained from the IRS by the ACLU pursuant to an FOIA request demonstrate that the IRS believes that it can snoop into private email without first obtaining a search warrant. The warrant, of course, would require the IRS to convince a court both that they know with some specificity for what they’re searching and that they have probable cause for the searching.
According to a 2009 IRS employee handbook, though, the tax agency said the Fourth Amendment does not protect emails because Internet users don’t “have a reasonable expectation of privacy in such communications.”