about 20 unread messages emails sent at once

Trying to troubleshoot something, and maybe it is normal behavior. All at the same timestamp, about 25 emails went out, all to different people. The email was (with appropriate substitutions):

Hi [username],

you have unread private messages on [sitename]. Please log in to read them!

[website domain name]


Problem is there was no private message waiting in the mailbox for them. Any ideas on what went on here? Checked the FAQ but those 2 scenarios do not apply. 2 of the emails received were to my test user accounts.

Thanks!

These are "forgetmenot" messages. They are sent when unread messages are in the mailbox (not new one). To avoid high traffic max. 25 messages are sent at once.

Ok great thanks. So I understand better now, if these users choose to NOT read these emails will they continue to receive reminder emails or is it a one time reminder (hopefully).

Also, if only 25 send at a time when do the others send, how often does the script run, once per day?

Thanks

Whenever Joomla framework is invoked, 25 messages (max.) are sent. The users will continue receiving these messages each n days (see backend configuration).