@mailpoet Thanks for the quick response.
1. Other than the MailPoet, I have the following plugins:
Akismet Anti-Spam
Autocomplete Address and Location Picker for WooCommerce
Contact Form 7
Nextend Social Login
Smart Coupons For WooCommerce Coupons
Woo Discount Rules
WooCommerce
WooCommerce Advanced Product Labels
YITH WooCommerce Wishlist
2. Version 3.101.1 didn’t help.`