This weekend Europe changed to summer time (daylight savings time). The clock was set one hour forward. And for some years in a row AcyMailing 5 has a problem with that. The next sending time for smart newsletters is automatically set a few hours later than the originally scheduled time and the time of the last sent mails is also changed a few hours different from the actual time they were sent. Normally we schedule mails to be send Thursdays at 16:00 h. Today I noticed the schedule was set to 21:00 h. This happened last year (and even before) too.
