How many emails is recommended to use in BCC with php mail() function?

Question

I am using php mail() function to send a newsletter (this function works well for me because right now I only send a few k emails a week), I am currently looping mail() function foreach email i need to send, but I was thinking about using BCCs to send more emails on each loop so it will take less time to process, whats the recommended amount of emails I should use for BCCs in php's mail() function?

Note: I am working on a implementation of phpmailer class but that will be for next months because I want to do a good script with that, right now mail() function is enough for me.

Answer 1

As per RageZ's comment, the limit is imposed by the SMTP relay or local spool. For Postfix this is default set to 50 recipients per message, Sendmail & Exim are unlimited, Microsoft Exchange 2003 defaults to 5000.

Postfix:

• http://www.postfix.org/postconf.5.html#default_destination_recipient_limit

Sendmail:

• http://www.sendmail.org/m4/tweaking_config.html#confMAX_RCPTS_PER_MESSAGE

Exim:

• http://www.exim.org/exim-html-4.30/doc/html/spec_14.html#IX1267

For comparison purposes, Microsoft Exchange:

• http://technet.microsoft.com/en-us/library/aa995735(EXCHG.65).aspx
• http://technet.microsoft.com/en-us/library/bb676532.aspx

Answer 2

You should know that you'll never have as good deliverability from your own server compared to using an email marketing service. Even if you were to become a domain expert in e-mail systems and configured your servers identically to theirs, they'd still deliver mail where yours end up in junk folders or rejected.

Check out

http://sendgrid.com/

http://postmarkapp.com/