You can have have different layouts for tickets that are printed on a thermal printer and those you email by switching ticket formats. It will not switch automatically.
The easiest way to do this is to define thermal tickets as the default ticket. Then, define emailed tickets as special ticket formats. With these special ticket formats, they can be made with colors, lots of graphics, etc.
When you want to email tickets, switch the shows to be printed to a special ticket format. Then, the emailed format will be sent.
Of course, you need to switch ticket formats whenever you switch from thermal to emailed tickets. But, that is the only disadvantage.