1.) Is the best way of sending a single email to every subscriber to add
their address to the BCC list? Are there any foreseeable problems if the
list gets too big?
I wouldn't recommend this technique unless you have only a handful of
recipients, as many email servers impose a hard cap on the number of
recipients per message. (I believe Gmail has a 100 recipient cap, if I'm
not mistaken.)
2). Is there some sort of return code for addresses that are
non-existent?
No. Zend_Mail simply hands the message off to your mail server's queue.
What happens after that (i.e., delivery attempts, failures, etc.) is
encapsulated within your mail server's internal environment and is not
directly accessible to PHP.
If your goal is to detect bounces, I'd recommend using the "unique
address per recipient as a return-path" method. E.g., set your return
path to '[email protected]' where 12345 is some unique
identifier for the recipient. Then you can monitor the messages that
come into the bounce inbox, decode the address back into your unique id,
and set your software to disable the appropriate recipient.
--
Alex Howansky
