1) delivery time expired:
This means that the recipient mx server has not accepted the emails even after multiple retries. This is an issue at the recipient end, and we do not have any control over this.
2) temporarily deferred due to unexpected volume or user complaints:
Due to huge amount of traffic, the emails have been deferred, i.e, set to be reattempted later.
3) 96.103.145.164 - "smtp;554 resimta-a1p-087381.sys.[[ recipient domain name ]] resimta-a1p-087381.sys.[[ recipient domain name ]] [[ IP address ]] found on one or more DNSBLs" :
This means that the recipient domain is in a blacklist. In this case the domain is listed on DNBSL.
4) unknown reason / message rejected:
These are offline bounces. In such cases the emails are accepted by the MX server at the first attempt and later it gets bounced with the actual response. Hence, in the logs it would be updated only as "message rejected" or "unknown reason".
5) Message blocked Your message to [[ recipient email address]] has been blocked:
This seems to be custom spam filter at the recipient end which is rejecting the emails. Kindly have this checked with the mail server admin of the recipient with the attached logs to get this resolved.
(Raise a ticket to Email Experts)
6) 143.244.202.96 - 4.4.1 (no answer from host)):
This means that there was no answer from the recipient MX server to accept the emails, hence the emails were soft bounced after multiple retries.
7) 142.251.10.26 - smtp;452 4.2.2 The email account that you tried to reach is over quota. Please direct the recipient to https://support.google.com/mail/?p=OverQuotaTemp:
This means that the mailbox that you are trying to reach has reached their limit to receive the emails from your domain. Hence the email to this recipient address was soft bounced.
8) 5.1.2 (bad destination system: no such domain)):
This is a delivery issue at the recipient domain as our delivery servers was not able to locate any destination domain/server to deliver the emails.
9) 142.251.10.26 - smtp;550 5.1.1 The email account that you tried to reach does not exist. Please try double-checking the recipient's email address for typos:
This is a delivery issue at the recipient domain as our delivery servers was not able to locate any destination domain/server. The email account/email address does not exist in this scenario.
10) 67.195.204.77 - "smtp;554 30 Sorry, your message to [[ recipient email address]] cannot be delivered. This mailbox is disabled (554.30).”:
Emails were soft bounced as the recipient mailbox is disabled or cannot be found.
11) 67.195.204.77 - "smtp;552 1 Requested mail action aborted, mailbox not found”:
Emails were soft bounced as the recipient mailbox is disabled or cannot be found.
12) 5.4.4 (unable to route: no mail hosts for domain):
This is a delivery issue at the recipient domain as the delivery servers were not able to locate any destination domain/server to deliver the emails.
13) 52.101.68.4 - "smtp;550 5.7.1 Unfortunately, messages from [[ IP address]] weren't sent. Please contact your Internet service provider since part of their network is on our blocklist(S3150):
This is a delivery issue and for scenarios like this, we request you to raise a request with us and we will check the same and update you on this email delivery issue.
(Raise a ticket to Email Experts)
14) 52.101.11.9 - smtp;550 5.4.1 Recipient address rejected: Access denied.:
This means that the recipient address was rejected with reason access denied. This must be checked at ESP end internally.
(Raise a ticket to Email Experts)
15) 81.7.169.208 - smtp;550 5.1.1 < [[ recipient email address]] >: Recipient address rejected: User unknown in relay recipient table:
This means that the recipient address was rejected with reason access denied at our end. This scenario must be checked at ESP end internally.
(Raise a ticket to Email Experts)