Anyone else have this problem?
Mailchimp‘s scheduling tool for “optimization for maximum engagement” doesn’t work for me.
It suggests different “optimized” send engagement times based on when I’m doing the work of scheduling.
Last night on 9/25,  I tried to schedule 9 industry-specific newsletter sends for the next day (today 9/26) – all of the ones that were suggested were slotted for 7pm or later.
I got cut off because the tool must be used 5 hours before the end of any given day (which is odd in and of itself), so I popped in this morning at about 8:15am to schedule for today.
This morning the very same 9 newsletters were “optimized” to send at either 9am or 10am today. Keep in mind that nothing changed in these newsletters other than me optimizing them at 815am on 9/26 instead of 6:30pm on 9/25.
I’ve noticed that if I try to “optimize” sends in the afternoon or early evening, MailChimp tends to slot them for send times that are late in the following day, but if I do this in the morning, it slots earlier times.
That’s not optimal… Anybody else?

Update from being on chat-hold:
While I was on chat-hold with Mailchimp, I did find this seemingly helpful article which generalizes that Tuesday/Wednesday/Monday are the best send days, in that order, and that 10am or 1pm’ish are the best send times (of course that still leaves the time zone issue.)  See the rather detailed article here.  I didn’t do an exhaustive search in the 10 minutes I was on hold, but it’s something.  🙂

Update from Mailchimp:

Jeremy (Mailchimp)

Sep 26, 2:17 PM EDT

Hey Scott,

Thanks for your patience as we’ve looked into this.

I was able to reach out for more clarification as to what happened here.

The information that controls the Send Time Optimization is based on the information we receive about the subscribers being sent the campaign from every audience they’re on in MailChimp.

This information constantly updates, so the results of enabling this at two different time periods, even within 24 hours, can differ based on this information.

I’ve had this ticket escalated to confirm, and from what we’re seeing, the Send Time Optimization is functioning as intended.



Thank you for that answer and your relatively speedy customer service on this complex issue. 🙂 I would offer up for consideration that this answer means to me that while it is functioning as intended, Mailchimp’s intention is flawed.

First, there no logical reason for two send times on the same day to both be optimal. Optimal means best. Both a 9am send and a 7pm send on 09/26 can’t be equally optimal – unless I guess of course if there’s no actual difference in optimization which would make the function irrelevant. If that’s what the data is telling you, then the function of data analysis for the purpose of optimization seems wrong to me.

Second, if the optimization can be so dramatically swayed by a 12’ish hour time delay, then that’s also a concern. I would expect a more firm “optimized send time” conclusion over a better period of time that would average out just such a fluctuation as caused by any single 12 hour period.