I'm not sure if this is the right place to post this, but here goes...

For some reason, my website has stopped sending e-mails informing new users that their accounts have been created. Similarly, the website no longer sends e-mails to members who have just been "Authorized" to inform them of their acceptance (it used to do all this). I have confirmed that the e-mail templates have not changed (in Languages > Language Editor). Is there some other setting that might have been changed? 

Also note that it's not an "E-Mail Settings" or configuration problem, because I'm able to send e-mails to myself using the "Newsletters" feature. As well, users are receiving e-mails informing them their passwords have been reset. It is just the confirmation and authorization e-mails that aren't going through. Your help is greatly appreciated.

Thanks,
Evan