Need a Content Filter reading only first part of Message Body

[t.gembler]

Hello

I'am using a Content Filter on incoming messages which use a Dictionary to find Text like "Receipt of your below email is acknowledged with thanks." in the Message Body. Now i get also hits on mails from the text on mail history because its an Answers on an reply ...

Is there a possibilty to read only the first part of the message or just for eg. the first 500 characters ?

I am very curious about your answers 

Thanks,

Tobias

[Udupi Krishna.]

I don't think this is even possible. Regex can be used to count number of characters but I am haven't seen any examples out there to compare the content and number of characters with it.