False 'membership expired' emails sent to recurring payment members

On thursday and again today CBSubs system sent out over 25 emails to members telling them their subscription had expired; 8 of these were genuine expiries; all but two of the rest had previously paid by recurring payment, one as long ago as january; Looking at the payment notifications from Paypal, these payment are all marked PDT Success on the date of payment and the subscription records for each profile show the correct expiry date; informing members of the status of the expiry notifications they received has been an administrative nightmare...

You need to configure a grace period to allow the IPN to show up before the expiration date. This is configured under the Pricing tab of your plans and is highly recommend for everyone to configure this when using Recurring payments.

Usually for PayPal a 3 day grace period should be enough. This also covers cases where PayPal fails to charge their account and gives them time to correct that so PayPal can retry.

All my subscription plans have a 30 day Grace period; All these emails went out 28 on thursday and 5 more today saturday, regardless of the date of last payment (see attached spreadsheet that show last payments) 13 of them are for recurring payment subscriptions As far as I can tell, all the actual subscriber profiles show the correct expiry date.a year after the latest payment date

Then your site is not receiving IPNs. Check within CBSubs > Notifications to see if you're getting PayPal IPNs. Check within your PayPal account to be sure you've configured IPNs as instructed in the gateway. CBSubs can't renew recurring subscriptions if it's never told a payment was completed.

If payments did renew fine and you're using CBSubs Mailer to send the emails on subscription expiration date then be sure you've configured it to send shortly after they've expired and not on the exact date as it does not take into account grace period for those.

10 out of the 20 payments  that are false expiries are marked PDT 'success' in the notifications table; the others have earlier years listed but not all earlier years (compared to our Papal history.
the only mail configuration foe CB I have is in the integrations tab 'Send Emails'; I can't see any option to configure either the CB email or the CBSubs mailer plug-ins.
I can see no common factor in these subscription accounts that would cause these email notifications to be triggered all at the same time and day
For several of these records Paypal has recurring payments this year; for some of them CB shows a payment but no IPN record; for the others CB says subscription Expired and no payment or IPN
 

For several of these records Paypal has recurring payments this year; for some of them CB shows a payment but no IPN record; for the others CB says subscription Expired and no payment or IPN

It sounds like you do not have IPNs configured or they are not reaching your site. Within your PayPal account check the IPN history and see if they failed to reach your site for whatever reason. You can also retry the IPNs from there. PDT is a return to your site from PayPal during a purchase which will process the payment as well, but recurring subscriptions depend entirely on IPNs.