Failed to send magic link

[2023-04-29 04:37:51] INFO "GET /ghost/api/content/tiers/?key=9a58bfc052ad6f0ce5d2eed20e&limit=all&include=monthly_price,yearly_price,benefits" 304 12ms
[2023-04-29 04:40:20] ERROR "POST /members/api/send-magic-link/" 500 120119ms

Failed to send email. Reason: Email has been temporarily rejected.

"Please see https://ghost.org/docs/config/#mail for instructions on configuring email."

Error ID:
    f284cf50-e647-11ed-8179-dd5e025b2cb9

----------------------------------------

EmailError: Failed to send email. Reason: Email has been temporarily rejected.
    at createMailError (/var/lib/ghost/versions/5.45.1/core/server/services/mail/GhostMailer.js:68:12)
    at GhostMailer.handleDirectTransportResponse (/var/lib/ghost/versions/5.45.1/core/server/services/mail/GhostMailer.js:158:19)
    at GhostMailer.send (/var/lib/ghost/versions/5.45.1/core/server/services/mail/GhostMailer.js:120:25)
    at runMicrotasks (<anonymous>)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async MagicLink.sendMagicLink (/var/lib/ghost/versions/5.45.1/node_modules/@tryghost/magic-link/lib/MagicLink.js:71:22)
    at async RouterController.sendMagicLink (/var/lib/ghost/versions/5.45.1/node_modules/@tryghost/members-api/lib/controllers/router.js:374:17)
    at async /var/lib/ghost/versions/5.45.1/node_modules/@tryghost/members-api/lib/MembersAPI.js:309:13