You could create a metakeys in case you want to persist the email address data. On the public template you could have Label that shows "Email address" and anchor control that gets the data from the metakey.
For instance you could add the following in the public template
"mailto:firstname.lastname@example.org?subject=<asp:Literal runat='server' Text='<%# ((CmsContentBase)Container.DataItem).GetMetaData("
CustomValue").ToString().Replace("&", "%26")%>' />
You could use the same expression for the mail as for the subject if you store the email as metakey
the Telerik team
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Public Issue Tracking
system and vote to affect the priority of the items.