Batch adding text to email subject lines in Outlook

[paulkaye]

At our firm, we put file numbers in all communications with our clients. However, we frequently begin dialogues with potential clients before opening a file for them. Then, once they become a client and we open a file, we have to go back and manually change each un-numbered email subject line. It's normally pretty easy to come up with a search term that finds all the emails that need changing, but it's time-consuming to change each one manually. Is there a way to batch insert a string that looks like "[12345]" (without quotes) into the subject lines of all the emails in a search result and/or folder? It's not very important if the string is inserted at the beginning or end of the subject line.
Many thanks in advance,
Paul