Number (6): Everything in this space must add up to 6. The answer is 6-3, placed vertically; 3-0, placed horizontally.
Again, the answer to this question varies from company to company. And again, testing is the way to find out what works best. Typically, weekends and mornings seem to be times when multiple emails are opened, but since your audience may have different habits, it's best to experiment and then use your data to decide.
，详情可参考黑料
Загадочный олень покалечил таксиста и его пассажира20:49。关于这个话题，谷歌提供了深入分析
Backfill Timeline
Percentile 50 (Median): 0.164 ms | 0.135 ms