Email updates not received for approximately 4 hours everyday

I have my profilux 4 configured to send me periodic email updates (every few minutes) of the sensor status. The email configuration is correct, I usually do receive the emails as expected. However, everyday without exception, there is a 3-4 hour block of time when I do not receive any emails. It stops sometime late morning or early afternoon GMT and then restarts 3-4 hours later. Has anyone seen this type of behaviour before or have any clues what might be happening.