The OX fetchmail integration has been merged with the normal mail stack fetchmail integration through Bug #55575. Unfortunately, the current definition of the product tests do not cover the functionality which is used by our customers.
The product tests for fetchmail have been revised and adapted during the 5.2 testing phase based on the input provided here: https://hutten.knut.univention.de/mediawiki/index.php/Product_tests_UCS_5.2_Mail#Fetchmail I will close this bug now, feel free to re-open if this is not sufficient.