This reads like you're formatting the text in the control only. If your table field is short or long text, change it to Hyperlink and you won't even need mailto: in the control properties. If not, I think you'll have to use code because all you seem to be doing is changing how the control value looks.
EDIT - that's based on having an actual email address in the table as suggested in post 2. You're saying you have an email address in the control or field but you're showing some sort of placeholder value, which isn't a valid address.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.