Credit card has been declined after paypal weird IPN behaviour.

[nimc]

I built a B2B service and I try to test the system pretending to be end-user buying digital product from my direct customer.

Last night I was trying paypal button to test the payment with my credit card (check out as a guest) and something weird happened.

Paypal was trying to send multiple IPN to my service which it took like forever. (If pay with paypal then it works perfectly fine).

Look at the time, paypal is retrying for 10 minutes.

I had to turn off the IPN because it was linked to my sendgrid account on the backend and sendgrid start sending multiple email to Gmail.

(which I fear that Gmail would mark my sendgrid as a spam).

Then I went to bed and this morning I turned my IPN on again to test but paypal said "Your credit card has been declined. Please try another one."

So I asked my friend to test with his credit card. But it appeared that his credit card has been declined too.

However, this morning I can receive/send payment with my paypal account. So I think my paypal was not limited. (I'm not really sure how limited looks like)

What could be the problem here?

PS. My credit card is not expired.

Thanks.