set PREFIX in outgoing email as non mandatory please

Hi,

we are dealing with few customers, who complains about prefix in the subject. Some of them are changing the statuses of their tool by first word in subject, so with JIRA it is impossible to work with them without annoying workarounds. 

I have to send emails to our outlook instead of to the customers and use script to delete first word in subject and forward to the customer, only because mandator prefix.

please consider this change, thanks

Jan