Guides & Tutorials

Delivery response codes

SMTP response code
0 No emails have been sent to the subscriber yet.
200 Delivery successful.
4xx or 5xx SMTP status codes.
1001 Subscriber unsubscribed in the latest campaign.
1002 Subscriber reported the latest campaign as spam. Is automatically unsubscribed.

Look at more examples from The most common response codes.

Classification
ok Message has been successfully delivered.
bad-mailbox Message recipient is non-existent, inactive or disabled.
blocked Delivery has been denied from Smaily (or any service).
expired Message delivery has taken more than the maximum amount (2 days) of time.
inbox-full Mailbox quota overused by recipient.
message-size The message is too large for the receiving email server.
routing-error Invalid (or non-existent) DNS entry or domain name.
signature-error Incorrectly configured SPF or invalid DKIM signature.
spam Message has been identified by the receiving email server as SPAM. Determined by the content or sender of the message.
transit-error Hourly/daily sending limits exceeded, receiving system is under heavy load or undergoing maintenance.
unknown Message status unknown.
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