What is "time" in the Einstein feature of Marketing Cloud?
Is the time used by Einstein (e.g. STO) CST? Or does it depend on the BU time zone?
For STO / personalized send time optimization it does not matter what time zone is used. In other words if "my optimal time" is 4 am in the morning "Einstein time" because I am in another timezone than Mr Einstein, that is absolutely fine.
For me, that might be 10 am.
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For the dashboarding view, the setting is in the STO menu:
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You can set this up via setup.
This setting can be defined at BU level.
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In cases of insufficient data, Einstein's "optimal default time" analyses the entire account. This sounds like it could get wild in international orgs. E.g. if there is a massive skew towards US data, people in Europe get their mails during the night as that's "typically a good time".
I guess here you'd better go with the alternative default option of "Send Immediately"