I would like to use the mail() function with a BCC: header that has a comma-delimited list of about 300+ email addresses.

Are there any limitations that I should know about? For example, is there a limit to the size of the string in the BCC: header or maybe I need to increase the script timeout in php.ini?

Any foresight on this would be greatly appreciated since it is kind of difficult to test something like this when you are sending an email to several hundred different people. Speaking of ... any ideas for testing the above would also be greatly appreciated.