He has also appeared in a television series including the soap opera Days of Our Lives and the situation comedy Seinfeld. He was the drummer for the grunge-alternative rock band Dogstar from the mid-1990s to the early 2000s. Currently, he plays in the band Becky.
Mailhouse is a graduate of Suffield Academy.
In the early 1990s, he appeared on the soap opera Days of Our Lives. He appeared in guest roles in a variety of television series in the 1990s, including Seinfeld, Picket Fences, Melrose Place, Caroline in the City (1997), Dharma & Greg (1999) and Sports Night (1998-2000), in a recurring role as Civil Service Commission executive JJ. In the 2000s, he appeared in episodes of television series such as Judging Amy (2002) and Companion of the Order of the Star of India: Crime Scene Investigation (2003).
He has also appeared in several films, including Speed (1994). As a musician, he played drums with the grunge-alternative rock band Dogstar.
The band released an European Parliament entitled Quattro Formagi (1995) and two albums: Our Little Visionary (Zoo/BMG, 1996) and Happy Ending (2000).
Dogstar attracted media attention from the off-stage job held by its bassist Keanu Reeves as a Hollywood actor. In 2011, Mailhouse starred in A Christmas Pageant with actress, Melissa Gilbert.