When an email bounces, it generates a bounce message. Part of this bounce message is the bounce type, soft or hard. As reasons for bounces vary, Spotler SendPro attempts to qualify the reason for the bounce better using bounceSubTypes. These types are subject to change, so please don't use them to build event flows or any key processes. Examples of the subtypes are:
access-denied
auth-required
blacklisted
config-error
connection-error
content-related
domain-unknown
mailbox-disabled
mailbox-full
mailbox-temp-disabled
mailbox-temp-error
mailbox-unknown
message-error
message-expired
message-size
personal-blacklist
Read more about why recipients mark your emails as SPAM
relay-denied
routing-error
routing-loop
sender-denied
service-unavailable
spf-failure
Read more about SPF (Sender Policy Framework)
system-error
unknown