PHP Mass emailing

Question

I work for a small marketing company that has asked me to develop a PHP application to send emails for their company without getting blacklisted or emails showing up as spam

Answer 1

The best way to be not be considered as spam and not being blacklisted is to send legitimate emails.

There is no problem sending a lot of mails from the same IP if no recipient mark it as "spam" at the end. To achieve this, a lot of things have to be taken into consideration:

1. Having good lists with opt-in is not an option.
2. Track bounces (both soft and hard), so you don't send unnecessary emails (don't send again emails to hard bounces, try again sometimes for the soft bounces and remove them if successful).
3. Run spam tests before sending bulk (SpamAssasin, etc.) (no advertising, but Litmus does that)

In fact, if you do everything good, your IP can end up with a good sending reputation and more mails will get to the inbox. Also be aware that when sending bulk, not everybody gets the email at the end. Some of them are "lost" by different filters in the middle of the process.

If you never sent mail from an IP, try to be progressive and do not send 1 millions the same month. I advice you to be progressive on how many mail send 1 IP.

Look at what specialized companies do. For example, you can learn a lot from Campaign Monitor and MailChimp. They have really great blog and resources to look at. Follow their blog, keep informed.