Mass marketing, relationships and trust.
One-to-many marketing/fundraising relationships are the same as personal relationships.
Trust is essential.
But, if you send spammy emails and direct mailers that are impersonal, irrelevant, interruptive, and annoying, your supporters won’t trust you or your employer.
They’ll feel that you abused the permission they granted you when they opted in to receive your communications (assuming they opted in at all).
Then, once they’ve lost trust in you, they’ll no longer want a relationship with you and, they certainly won’t give.
So as you prepare your next one-to-many marketing/fundraising communication, behave the same way you’d conduct yourself in a one-to-one personal relationship.
Because mass marketing can only be used to build relationships if it builds trust.