Apple / SMTP error code 421
smtp;421 4.7.1 Messages to example@icloud.com deferred due to excessive volume. Try again later - https://support.apple.com/en-us/HT204137
Medium severity
The email address is currently receiving an email at a high rate. Sending email in the future will most likely be successful.
Documentation
▓▒█▒▒▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▒▒█▒██▓▓▓▓▓▓▓▓▓█▒▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓███▒▓▓███▓░█▓▓▓▓▓▓▓▓▓░▓▒▓█░▒░░░█▓▓▓▓▓▓▓▓▓▓░▓▓▓▓▓▓▓▓▓░▓▓▓▓▓▓▓▓▓▒█▓░▒██▓▓▓▓▓▓▓▓▓█░▓▒░▒▒▓▓▓▓▓▓▓▓▓▓▓▒▓▓░▒█▓█▓▒█▒█▓▒▓▒▒▓▓▓▓▓▓▓▓▓█▓▓▓▓▓▓▓▓▓▒▓▒░▓▓▓▓▓▓▓▓▓▒░▒█▒░▓▒▒█░▓▒▓▓▓▓▓▓▓▓▓▓█▓█▒░▒▒▒░█░▒█▓▓▓▓▓▓▓▓▓░░▓▓▓▓▓▓▓▓▓██▒▒▓▒░█▓▒░▒▓▓▓▓▓▓▓▓▓▒█░█▒█▓█▒▓▒▓█▒░████▓▓▓▓▓▓▓▓▓▓▒▒▓▓▓▓▓▓▓▓▓▒▒▒█▓▓▓▓▓▓▓▓▓▓▒█▓░▒▓▓▓▓▓▓▓▓▓▓▒▒▓██▓█░░░▒▓▒██▒▒▓░▓▓▓▓▓▓▓▓▓█▒▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓░▒▒▓▓▓▓▓▓▓▓▓▓░█▒░▓▓▓▓▓▓▓▓▓░▓▓▓▓▓▓▓▓▓░▓▓▓▒▒▒▓▒▒▓░▓▒▒░█▓▓▓▓▓▓▓▓▓▓░▒▓▒░█░░▓▒░▒█▓░▒▓▒░░▒░▓▒▒▒░▒▒▒▓▒▒▒▓▓▒▓▒░▓▓▓▓▓▓▓▓▓█▓▓▒▓▓▓▓▓▓▓▓▓▒▓░▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▒░█▒▓▓▓▓▓▓▓▓▓▓▒▒▒▒█▒▒▓▓▓▓▓▓▓▓▓░▒▓▓█▒▓▓▓▓▓▓▓▓▓░█▒▓▒░▒░░▒█▓▓░▓▒▓▓▓▓▓▓▓▓▓█░▓▓▓▓▓▓▓▓▓▒▒█▒▓░▒░░▓█░▒▓▓▓▓▓▓▓▓▓▒▒█▓▒▓░▒░░░▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▒▒███▒▓▓▒▓▓▓▓▓▓▓▓▓▒██▓▓▓▓▒▓▒▓█░█▒▒░▒▓▓▒▒▓▒▓▒▓░▓▓▓▓▓▓▓▓▓▓░░▒█▓▒░█▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓░▒▓▓░░▒▒▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓░▒░▒▒▒█░▓░░▓▓▓▓▓▓▓▓▓▓░▓▓▓▓▓▓▓▓▓▒▒▓▒▒▒░▓▓▓▓▓▓▓▓▓▓░█░░▓▒▓░▓▓█▓▒▒▓█▓▓▓▓▓▓▓▓▓▒▓▒▓░░█░░░▒▓▒▒░░░░▓▒▒▒▒▓▒█▓░░░▒░░▒█░░░░▒▒▒▒░