Hello @UCCoM1819 ,
Your email's open rate will only reflect unique opens, not all opens, so those numbers won't be changing if the same people are regularly looking back at your emails. Additionally, updates to sent emails' reporting will diminish in frequency over time to avoid server overloads. For the first 48hrs, all data should be updating at least every 10-15 min, then after the first week it'll begin updating much, much less frequently. It will, however, continue to track that info as long as you have an actively paid account.
Also, keep in mind that opens tracking requires the 1x1 pixel tracking image to be downloaded / viewed in the email program - so if these new openers or their email clients aren't allowing images to display then it won't be able to reflect on the email's reporting.
See also:
Email reporting overview
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