Hello OJS user
Our team would like to share our solution on the fixing of the bulk email bug that happened on the OJS 3.3.x version. The bulk email sending such as used by announcement and other multi email sending is a known bug that can be found here and many of our clients outcried for this bug. To help them and this community, our team initiated fixing this by releasing a free plugin.
This fix is made possible with the flexible hook system on OJS, you get and check the details of this free plugin here. :