I have a website for a client which allows them to email their users, which is handled using PHP's mail function and a BCC header. This works on the tests I've done to a few addresses but the client doesn't think it's working when sending to all their customers (just over 2000).
I've read about the limit of 998 characters on any one line but does this apply to headers too and is it still relevant?
I'm also wondering if there's a limit to the number of addresses that can be included in a BCC field but googling hasn't really given me an answer.
Does anyone have any thoughts/advice on this? I'm going to ask the ISP if there's a limit on sending mail too in case that's the problem.