Cannot send session cache limiter – headers already sent

Apart from the above error, the plugin does not work in multi setup going into an endless loop of sending innumerable emails by continuous refresh

@jorge: This would indicate your php.ini file has
display_errors = On

For security reasons you should turn display errors off:

display_errors = Off

See this article for more information on the recommended settings for your php.ini file: https://www.wpsecuritychecklist.com/securing-php/

@anup: The plugin has not been tested in a multi site environment. Your experience could indicate that it does not work in multi site.

Is this error totally harmless? (Assuming it is not viewed by visitors…)

I noticed this error, but everything seems OK. I just wanted to check if there might be some hidden problem I am not aware of.

I did notice that my php.ini file was not configured for security, so fixed that, and thanks for the message on that.

I just am curious about the original error–it no longer displays because we turned off display_errors, but what it seems like we should fix the error. Sorry, I don’t have any php experience, so I don’t really understand what is going on.

It’s a warning message and it is not a source of concern.