How many times do you open your Inbox to find the same old message from a company that seems to contact you almost every day, offering a product or service for which you have no current need? Most of us simply press "delete" rather than scrolling to the bottom of the page and unsubscribing. Thus, although you haven't physically opted out of the email list, you have mentally opted out of emails from the company.
This mental opt-out has the same negative impact as actual opt-out or do-not-contact lists for marketers trying to reach their target audience. If a potential customer doesn't even take the time to read an email, the result is the same as if they had added their name to the unsubscribe list.
Relevant emails avoid the "mental opt-out" which happens when marketers bombard their customers with too many blanket, untargeted email messages. Often, marketers suffer from the notion that email is free, so they feel they have nothing to lose financially be sending out regular emails to their contact lists. However, each irrelevant or untargeted email a customer receives has a detrimental effect, silently chipping away at the chance that the recipient will take the time to open and read the next one.
By taking time to understand each customer as an individual, and using the technology available to fine-tune frequency, cadence, tone and message of emails, organizations can connect with their customers in a relevant and timely manner which will likely be read and well-received.