New research by security firm McAfee has found that spammers are trapping users across Europe by using messages disguised as legitimate reply emails containing “out of office” or “undeliverable” in the subject.

The research looked at the impact spam is having on international commerce and the reaction to it. One impact of spam is to block an IP address based entirely on geolocation or by blocking access to emails containing foreign languages, the report said.

“Actions such as these generally stem from foreign-language spams reaching executive decision makers who then demand an administrator respond to specific language-based criteria,” the report said. “These sorts of policy decisions are unlikely to be regularly reviewed, and represent a digital bias against certain languages or countries that could affect legitimate communications.”

The report turned up some interesting finding about the tactics used by spammers to target UK businesses.

Bounce-back emails, those containing ‘failure notice’, ‘undeliverable’ and other similar messages, were very popular with addresses ending in .com, filling four of the top ten spam subjects. Half of the top ten spam messages sent to .org addresses contained bounce-back subjects, including four of the top five.

In the UK however the domain .co.uk contained no bounce-back emails in the top 15. Spam email subjects here tended to be much more bizarre, with headings such as “Salute, man!”, “I’m locked in room”, “Your house switched off” and “What’s with bar?” registering.

“Given that United Kingdom spam is also in English, we might assume that techniques that work in the U.S. country code would also work in .uk. However, that’s not the case, so we imagine that U.K. email addresses have been left out of the forged From addresses through some conscious action by spammers,” said the report.

“We don’t really know whether someone chose one country code over another,” the report continued. “Perhaps an algorithm merely appended .com or .org to the end of a randomly generated string, but the practice stands in stark contrast to spam behaviour in the .us world.”