There are hundreds if not thousands of people online offering technical and content advice on email marketing for business as well as for fundraising or campaigning. I'm not a technical expert so can't pretend to understand detailed coding or firewall issues but I do know a thing or two about content and about engaging readers.
Why do we want to engage readers? Because engaged readers are much more likely to do what you're asking them to do! Note the implication in that last sentence... you have to have a clear and compelling 'ASK' in every email whether it's for funds, to buy something, to sign-up to a campaign, to share with a friend or just to get further information - include an action.
I received a well-intentioned and polite email earlier this week from someone telling me about a schools reading project in Wales. Here's how it broke down: