Office workers across the country are on alert amid fears that the postal bomber may strike for a fourth consecutive day.
Police have urged companies, organisations and individuals to be careful when handling mail and alert them to suspicious packages.
The full extent of the letter bombing campaign has become clear as police revealed details of seven linked attacks in the last three weeks.
Homemade pyrotechnic-style bombs in A5 jiffy bags have been posted to seven different businesses across Britain since January 18 - six of which supply services or technology to law enforcement agencies.
The partner of the latest letter bomb victim told how she rang him up and said: "Hi babe - I've been blown up."
Karen Andrews, 35, was hurt when she opened a letter bomb at the Driver and Vehicle Licensing Agency (DVLA) headquarters in Swansea.
Her partner Tony Clare, 38, told the Daily Mirror: "When I spoke to her on my mobile phone her first words were: 'Hi babe - I've been blown up."
In a statement, she said: "I was shaken, shocked and frightened. It's hard to describe how I felt. Everybody started running around me and I felt quite calm, but I didn't really know what had happened."
Three of the bombs were sent to forensic laboratories in Oxfordshire and the West Midlands area last month and another three to traffic enforcement companies in London, Berkshire and south Wales this week.
The other was sent to a house used as a business address in Folkestone, Kent, on Saturday. At least nine people have been injured in the blasts.
