Hi, I am not sure of how these e-commerce sites sending tons of mail daily? does it acceptable in dedicated hosting? or does they purchase seperate e-mail hostings , or does they setup there own email servers with ms email exchance? And that too they are sending mails with unsubscribed members.. how
usually they use 3rd party services to send newsletter. Mailchimp.com SendBlaster.com Aweber.com Icontact.com Be carefull using this service, your email sender could marked as spammer.
You just need to choose a reliable email marketing service provider to fulfill it. Comm100 Email Marketing is another solution.http://emailmarketing.comm100.com/
Larger companies tend to use dedicated email servers, sometimes through a relay with a tool such as SendGrid. There are pros and cons to both self hosting email servers or using a third party, general rule of thumb is smaller email lists are fine on a third party platform, larger lists (On the business I have worked with on this, 50k+ is usually when we first start looking at this) will move on to a dedicated server and use software such as Octeth OEM Pro or similar to manage the email delivery.
They can send a lot of emails a day to customers. In the long run, however, it is quite harmful because customers are starting to get nervous. You have to think well about what to send, when and to whom.
Yes, then person is your subscriber, it doesn't count as spam, as far as you email that person 7 days a mouth. From my experience, we used Amazon AWS SES product (10'000/24h) and mailchimp.com pay as you go plan.