Your experience with mass mailing users?

I have a question for those journal managers who have large numbers of users set to receive notifications. If you have a few hundreds or over 1000 users, do you still send emails automatically from the system? Is there a risk that your organization’s mail server would be blacklisted by other servers?

I am considering splitting our list of 1200 users into smaller chunks and sending emails manually from Outlook. But if in your experience there is no problem sending one mail to all users, no matter the number, it would be interesting to hear.

Some points from our experience with this hosting hundreds of journals, some with many users.

Depending on the normal volume of messages sent in the SMTP used, a sudden increase in sending can cause some temporary blocks

Some users mark OJS messages as spam by mistake. In mass mailings this tends to occur more frequently, significantly increasing the possibility of other messages from OJS falling into the spam folder for other users.

If the OJS in question suffers from automated registration (bots), it is important to block the entry of new bots, if this still occurs, and clean the user base.