The Question: I know I can specify multiple email addresses in the BCC field by comma delineating them. But I'm wondering if there is an upper limit to how many email addresses can be attached this way. Is there any upper limit? Are there performance considerations? Is the limit within PHP or the mail server or a combination of both?
Hello!
I would not send any e-mail messages by Bcc field. One of the reasons is that many antispam software blocks e-mail that does not have the recipient's e-mail address in To or Cc fields.
My suggestion is that you will use an external mailing library, for example phpmailer (http://phpmailer.sf.net) to properly encode the content, recipient, subject etc.
Then, you would send each e-mail separately and set the final recipient in the Form field on each loop. This costs some performance, but is more reliable and better way to send the messages. There is also no upper limit set by external server, you can send 5 or 5000 e-mail messages.
If the amount of recipients raises high, I would suggest you to send the e-mail messages in the background in another process. When an user completes the newsletter in the website, you will save the newsletter also to the database and send the messages later with a cronjob.
Best regards, Ville
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