Merseyside Police reopened its investigation in February. Woodhouse was later arrested and questioned.
But Fadden has since learned Merseyside Police will not be taking any further action.
In a letter from a Merseyside Police detective constable, she was told: “At the time of the incident a number of other offences [besides malicious communications] could have been considered and were maybe more suitable for this incident, including harassment.
“However, as harassment is a summary only offence then it carries a statute of limitations of six months so would have expired back in June 2022.
“This is why the matter was progressed with malicious communications as it is the best suited offence available, as it does not carry a statute of limitations.”
However, he said while the letters were “offensive in nature”, the “Police Decision Maker does not believe that they go beyond the limits of what is tolerable in society, aiming to shock, insult or degrade the victim”.
Fadden said she was disappointed that the opportunity to prosecute Woodhouse had been missed.
“They said they didn’t know how to contact me [when I left my job], but they had my phone number.
“When I went back to them, they told me they’d found a fingerprint on one of the letters.”
She added that she “knew the police have got a hard job, and they’ve not got the resources they need”, but that “if they had done what they needed to four years ago”, then Woodhouse’s campaign against Banks may have been avoided.