There are a few reasons:

    • Your domain age is under 30 days.
      There is a new policy which Blocking NODs (Newly Observed Domains). The following rules added to your domain by default(We can’t do anything)
      • SEM-FRESH — Domains registered in the last 5 days
      • SEM-FRESH10 — Domains registered in the last 10 days
      • SEM-FRESH15 — Domains registered in the last 15 days
      • SEM-FRESH30 — Domains registered in the last 30 days
      • DAY OLD BREAD — Domains registered in the last 5 days (requires Registration to use their DNSRBL)

      Solution: You have to wait for your domain to be removed from the SEM-FRESH list. It will be removed automatically.

    • Missing MX Records:

      Below is a list of all the MailWish MX records information. All have the same priority, we recommend adding them all for maximum resilience:

      Name/Host/Alias Time to live (TTL) Record Type Priority Value/Answer/Destination
      @ or leave blank 3600 MX 10 mx001.cloudus.rs.oxcs.net
      @ or leave blank 3600 MX 10 mx002.cloudus.rs.oxcs.net
      @ or leave blank 3600 MX 10 mx003.cloudus.rs.oxcs.net
      @ or leave blank 3600 MX 10 mx004.cloudus.rs.oxcs.net
    • Make sure your domain or IP is not blacklisted:
      Check here https://mxtoolbox.com/blacklists.aspx