Callaway Golf, Hydro Flask, and CustomInk all saw 58 percent open rates in emails during the week leading up to Father's Day, according to metrics from eDataSource. The company, which daily tracks more than 25 million emails sent by some 50,000 brands, found that 14,600 campaigns with the words “Father's Day” in the creative were sent out last week. CustomInk, alone, saw more than 64,000 opens based on its mailing to 111,000 addresses last Monday.