A total of seven people were held for questioning about anthrax alerts over the past three days, according to gardaí.
As a result, two files had been submitted to the DPP for possible action, and other individuals were still be interviewed.
A garda spokesman said "Files are being prepared with a view to having those responsible brought before the courts.
"The sending of bogus material is a serious matter and those responsible, if convicted, may face jail terms of up to five years."
The spokesman said members of the public were being reminded that if they received or discovered suspicious material, they should not attempt to move it, but immediately contact the gardaí.
Earlier this week, The Taoiseach Mr Ahern and Garda Commissioner Pat Byrne indicated there will be an early review of legislation relating to hoax mail.
Up to tonight, almost 40 cases of suspect deliveries had been made to gardaí since the start of the worldwide scare.