Beginning on February 1, 2022, Marketing Cloud will require multi-factor authentication (MFA) upon login as an additional security precaution. Learn more about MFA and how to enable it in this wiki.
Learn how to create a Data Extension as you typically would, then Import the data from a file (rather than 'start' it). Just remember, you'll need the Contact 18 ID to Import successfully.
When faced with a failed send, a send to 0, or failed Data Extension, review the items below. Often, the root cause is something over which you have control rather than a systemic failure in Salesforce or Marketing Cloud. If there is an outage or broad issue, users will be notified as soon as possible.
Understand the difference between sender profiles, delivery profiles and send classifications in Marketing Cloud. These not only drive email from information but also (more importantly) ensure CAN-SPAM compliance.
