- Make sure you are using Admin build 171 or above.
- Increase the PHP memory limit to 512MB or more if you have a lot of records – “memory_limit=512M” value in php.ini or “php_value memory_limit=512MB” in .htaccess. After you have done this Apache may need a restart.
- Set max_execution_time to 600 in php.ini so that it doesn’t time out while sending the emails.
Once the batch process has started wait for it to finish even if it looks stuck as a lot of records may take a while to process.