I've sent an email and within seconds got confirmation of delivery. The evidence PDF, however, shows a delivery time hours ahead.
Simple. All dates and times shown in the eEvid.Cert PDF are UTC-based and relative to the time-zone in which you live. In our case, UTC +01:00 in winter and UTC +02:00 in summer.
As you know, when your neighbors wake up in the morning, millions of others are going to sleep in the other side of the world. We all live in a 24h round-the-clock planet: New York's 11:37am are not Sidney's 11:37am also, but 01:37am, the next day. In stablishing the exact time in which a given email has been delivered, we need to take this into consideration.
In order to do so, all dates included in the eEvid evidence are given in Coordinated Universal Time (UTC), the primary time standard by which the world regulates clocks and time. Visit the Wikipedia to know more.