If you’re sending an email campaign to thousands or millions of user using some software then you’re going to need a reliable mail server. Most of the shared servers are not going to allow you send more email. There are a lot of restrictions and host may impose email sending restrictions which makes it impossible to send.

There are ways to send –
1. You can send emails out application your web host’s mail sending engine. This advantage is accomplished if you’re sending only a few hundred emails per month, about as soon as you go over this, your host will not allow you to send more. This option is good for sending email using online php tools so many are available please check with google 🙂
2. You can buy your own committed server from service provider like RackSpace.com or netatlantic.com (we are using this!) and configure it to send emails. We send 60000 emails per month without any issue, they have easy to use web interface. We just create newsletter test and send to our subscribers. It works perfectly.

3. Most effective option is using third party mail server like SMTP.com. Even if you are using shared server you can use there service if you have tones of email to send. Don’t forget to negotiate for discount if you are using there partners software!!