Hello @PatriciaW886 ,
If you need to do a resend beyond the manual and automated limits, I'd recommend using the Quicksend feature. Go to the list of non-openers in the email's report, select-all them using the top-most checkmark box, Actions dropdown > Quicksend. This can be done for up to 5k contacts at a time.
If you need to do a RSNO to more than 5k contacts, then I'd advise making a list from your non-openers, copying the email, then sending that copy to that non-opener list.
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