Setting up domain mail, how to pass authentication (SPF and DKIM records) for the Sendbox service?

Question

Email Marketing

Good day!
Given: Domain mail on Yandex.
Task: Make mailing from the mail of this domain through the Sendbox service from mail.ru
Problem: To make a "large" mailing, you need to set up SPF and DKIM records on the domain in order to authenticate the domain on the mailing service for further mailing. SPF and DKIM records entered, more than 72 hours have passed, the SPF record appeared, but DKIM did not. I also checked these records through other services, the DKIM record is simply not visible, as if it does not exist.. Technical support from Yandex, thought about it and does not answer.. Maybe they are not friends with each other at all..
Question: Can someone already set it up like that? What and how did they do it? How to get out of this situation?

Answer 1

DKIM is generated up to 2 days, just wait