Types of email Bounces
When an email cannot be delivered to an email server, it's called a bounce. The email server will provide a reason for the incident, and Our server uses those reasons to determine how to treat that email address. Different internet service providers (ISPs) bounce email messages based on their own rating systems and definitions. We categorize bounces into three types: hard bounces, soft bounces, and internal bounces.
HARD Bounce
INTERNAL Bounce
SOFT Bounce
Catch-All
HARD Bounce
A hard bounce indicates a permanent reason an email cannot be delivered. Here are some common reasons an email may hard bounce.
Recipient email address doesn't exist.
Recipient email server has completely blocked delivery.
Note
There are occasionally cases in which valid email addresses will hard bounce.
Error Codes:
smtp; 5.1.1 - Bad destination email address 'reject' (delivery attempts: 0)
smtp;550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient xxxx@demo.com not found by SMTP address lookup
smtp; Message bounced due to organizational settings.
smtp; 550 <xxxx@demo.com> No such user here
smtp; The email account that you tried to reach does not exist
smtp;554 5.4.4 SMTPSEND.DNS.MxLoopback; DNS records for this domain are configured in a loop
SOFT Bounce
Soft bounces typically indicate a temporary delivery issue and are handled differently than hard bounces by our server. When an email address soft bounces, it will immediately display as a soft bounce in the campaign report.
While there are many reasons an email address may soft bounce, these are some common reasons this could happen.
Mailbox is full (over quota).
Mailbox is not configured correctly.
Mailbox is inactive.
Recipient email server is down or offline.
Recipient email server has been sent too many emails during a period of time.
Email message is too large.
Domain name does not exist.
Email message blocked due to content.
Email message does not meet the recipient server’s policies.
Email message does not meet the recipient server’s DMARC requirements for authentication.
Email message does not meet the recipient server’s anti-spam requirements.
Email message does not meet the recipient server’s anti-virus requirements.
Email message does not meet the recipient server’s sender requirements.
Email cannot be relayed between email servers.
Email cannot be relayed for unknown reasons.
Error Codes:
BOUNCED BACK
smtp;554-5.2.2 mailbox full
554 5.2.2 STOREDRV.Deliver.Exception:QuotaExceededException.
MapiExceptionShutoffQuotaExceeded
smtp; 5.3.0 - Other mail system problem 554-'5.4.14 Hop count exceeded - possible mail loop
Failed to process message due to a permanent exception with message Cannot open mailbox
Now that you know what hard and soft bounces are, you can view bounce details in your email campaign report. It's a good idea to keep a close eye on your bounce rate to be sure your emails are reaching your contacts. This can help you to abide by spam laws and avoid bounce suspensions.
INTERNAL Bounce
Internal bounces may occur due to server complexities among other issues and not necessarily due to suspected email inaccuracies. For example, the recipient's email address may be valid, however the server might have difficulties delivering to a certain domain. We recommend considering another delivery server or try resending the email at a later time.
In email delivery, the ISPs (such as Gmail, Yahoo, Outlook etc.) automatically checks every option starting from the subject line, the content, the reputation of your IPs/domain, links inside the email and email frequency. These ISPs are quite restrictive when excepting emails when any of the below prompts are detected.
Spam triggers
IP/Server/domain may be blacklisted.
The range of IPs are recognized as blacklisted.
The URL embedded in the email content may be blacklisted.
Spam content in the subject line etc. (Related to the email content or your IP/domain's reputation)
Here are some other common reasons emails encounter an internal bounce:
Hop count exceeded - possible mail loop
All recipient addresses rejected: Access denied
Hop count exceeded - possible mail loop detected on message id
Message expired; connection refused
Other mail system problem, Sender denied
Remote server returned message detected as spam
delivery temporarily suspended
Message blocked. If this is a false positive, please report this to your hosting service provider
Error Codes:
smtp; 550 5.4.1 All recipient addresses rejected
smtp;554 5.4.14 Hop count exceeded - possible mail loop
X-Postfix; delivery temporarily suspended
smtp; 550 5.7.1 [CS] Message blocked
smtp;550 5.4.316 Message expired; connection refused
smtp; 450-4.2.1 The user you are trying to contact is receiving mail at a rate that 450-4.2.1 prevents additional messages from being delivered.
smtp; 5.3.0 - Other mail system problem
smtp;550 5.7.350 Remote server returned message detected as spam -> 550 5.7.1 Message rejected as spam by Content Filtering.
smtp;550 5.7.520 Access denied, your organization does not allow external forwarding
Catch-All
A catch-all account is an email address that collects all the mail sent to your domain name not sent to the other email addresses known to the server.
Any emails sent to misspelled recipients at your domain, for example, will be "caught" by the catchall account. For example, the catchall could be defined as all@domainname.com. Suppose an email meant for matt@domainname.com is actually sent, misaddressed, to matthew@domainname.com. The email will end up in the catchall mailbox of all@domainname.com. Without a catchall defined, the email would have been bounced back to the sender instead.
An advantage of the catchall is that it is like having unlimited aliases.
One disadvantage of a catchall is that more Spam may be sent to your domain since messages are not bounced but accepted by default to non-defined email recipients.
Types Of IP Address
There are four types of IP addresses: public, private, static, and dynamic. An IP address allows information to be sent and received by the correct parties, which means they can also be used to track down a user's physical location.
Our Server Fetches Address of recipients based on IPV4 and IPV6.
IPV4 IP Address:
Internet Protocol version 4 is the fourth version of the Internet Protocol. It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks.
Example:
172.217.168.238
31.13.84.36
151.101.0.84
IPV6 IP Address:
An IPv6 address is a 128-bit alphanumeric value that identifies an endpoint device in an Internet Protocol Version 6 (IPv6) network. IPv6 is the successor to a previous addressing infrastructure.
Example:
FE80:CD00:0000:0CDE:1257:0000:211E:729C
For any support assistance or doubts please feel free to contact IT operation.
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