best approach to form->mail digest

hi, I have a series of forms which are converted to emails. at this stage, the client is recieving way too many emails a day, and I wish to offer them a digest (multiple email in one). at this stage it goes something like: form filled in >> click submit >> email body is generated >> email is generated and sent i'm proposing the following: form is filled in >> click submit >> email body is generated >> if counter != 50 contents of body are written (added) to digest text file counter is increased by if counter >= 50 contents of body are written (added) to digest text file counter is reset to 0 email is sent, including the digest text file as the body anything stupid in this? anything I should watch out for? anything such as file locking I should be carefull of? any better ways? your collective knowledge is awaited eagerly :) Justin French Australia