It would be absolutely necessary for me - to preview a merged email after the merge before sending - to check for possible problems.
This is possible in almost al merge applications I use like MS-Word, Groupmail...
It is extremely embarrasing when sendnig a single email using an email template to a special customer and have the wrong fields merged or missing - and the customer thinks he got a mass email. - but currently there is no easy way of checking this.
regards
Alex