SMTP response codes fall within three main brackets:

SMTP 200 -> Positive acceptance code. eg: SMTP 250
SMTP 400 -> Temporary delivery fault (delivery will be retried) eg:450
SMTP 500 -> Permanent delivery failure (Non-delivery report (NDR) will be provided to the original sender eg: 550


Reason

Definition

Activity

450 4.1.1

Rejection when relay check is enabled

Blocked

450 4.1.8

Sender address rejected: Domain not found

Blocked

450 4.5.5

Header Checks Defer

Blocked

450 4.5.6

Temporary

Blocked

450 4.5.7

Temporary

Blocked

504 5.5.2

Sender address rejected: need fully-qualified address

Blocked

550 5.1.1

Recipient address rejected: undeliverable address

Blocked

550 5.5.3

Recipient address rejected: Multi-recipient bounce

Blocked

552 5.2.2

Sender/Recipient rejected

Blocked

552 5.5.2

Message size (content filter)

Blocked

554 5.5.3

e-mail Rejected Content Filter Size

Blocked

554 5.5.4

Spam IP, rejected at the boundary

Blocked

554 5.5.5

e-mail Rejected Spam

Blocked

554 5.5.6

Loop detection > 10 times X-everycloud-disclaimer

Blocked

554 5.5.7

e-mail Rejected Content Attachment

Blocked

554 5.6.1

Spam Header rejected

Blocked

554.5.6.2

Spam Link rejected

Blocked

554 5.6.3

Spam Body rejected

Blocked

554 5.6.4

Virus E-Mail Blocked

Blocked

554 5.7.1

unknown domain or unknown recipient (LDAP check)

Blocked

virus

Virus found (based on signature)

Virus

virus

Malware link, phishing or virus outbreak detected

Virus

admin-bl

Blacklist controlled by admin

Quarantined

ase-bl

Individual blacklist controlled by Support dep.

Quarantined

ase-recap1

Diffuse spam fingerprint

Quarantined

ase-rep1

IP reputation list1

Quarantined

ase-rep2

IP reputation list2

Quarantined

ase-rep4

URL / IP reputation list 4

Quarantined

bodytag

Spam signature in mail text

Quarantined

dirtyip

Reputation filter on IP basis

Quarantined

fingerprint

Re-captured spam mail by hash

Quarantined

header

Spam signature in mail header

Quarantined

link

Ads link

Quarantined

rbl50

pre-stage to 554 5.5.4 but not blocking yet

Quarantined

sameip

Signature recognition of spam engines

Quarantined

score

Dynamic contents evaluation

Quarantined

ScoreTag

Dynamic contents evaluation

Quarantined

spam

Reputation filter based on sender server

Quarantined

spamip-net

IP range of servers with poor reputation

Quarantined

spam-sum

Spam fingerprint

Quarantined

subjecttag

Spam signature in subject line

Quarantined

user-bl

Blacklist controlled by the user

Quarantined

wc

Spam pattern recognition

Quarantined

xarg

Bounce attack or individual customer rule

Quarantined

zombie

Botnet computer

Quarantined

content

Inadmissible attachment (content filter)

Content

admin-wl

Whitelist controlled by admin

Valid

asespf1

Known sender, type 1

Valid

asespf2

Known sender, type 2

Valid

ase-wl

Individual whitelist controlled by the support dep.

Valid

big2

Maximum mail size valid for spam check exceeded

Valid

bigmessage

Maximum mail size valid for spam check exceeded

Valid

body-wl

Whitelist signature in mail text, type 1

Valid

body-wl2

Whitelist signature in mail text, type 2

Valid

header-wl

Whitelist signature in header, type 1

Valid

header-wl2

Whitelist signature in header, type 2

Valid

knownsender

Sender address with positive reputation, type 1

Valid

noreason

Unevaluated mail

Valid

qsender2

Sender address with positive reputation, type 2

Valid

realbounce

Sent via bounce management

Valid

score

Dynamic contents evaluation

Valid

sender-ip

IP sender address has a positive reputation

Valid

subject-wl

Whitelist signature in subject line, type 1

Valid

subject-wl2

Whitelist signature in subject line, type 2

Valid

user-wl

Whitelist controlled by user

Valid

xarg-wl

Bounce mail or individual customer rule

Valid