Have to manually encode @ (or other special characters) when setting the username/password for an smtp sender

The attributes that end in and endpoint URI (for instance: smtp user and passwords) had to be encoded as a workaround for this issue. That workaround has to be removed when this fix is in place. Keep in mind that this also affects the result of MEL expressions (for instance, if an expression evaluated to a username with an @ char, it had to be encoded before using it), so a check has to be done to remove all the additional encoding that was placed for workarounding this.