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These email newsletter services probably send millions of emails per day.
How do they successfully do this without having their system black listed?
Don't services like otmail/gmail block emails if they reach a certain threshold from a single domain?
I'm interested in running a service that will be sending a lot of emails on behalf of other companies, so just want some tips/ideas on how they do it at such a large scale. (I might not be admining the box, but want an idea of what is involved technically)