Delivery errors are the errors during a campaign run when the subscriber's email service provider does not accept an email. The undelivered mail is returned with an error code. Email service provider may notify that the address does not exist or inbox is full or the server is unavailable, etc .
Thus the errors are divided into soft and hard.
- Soft or non-critical errors are temporary and may be eliminated, then your email will be delivered: for example, inbox is full or server is temporarily unavailable, etc.
- Hard critical errors are the errors that cannot be eliminated. For example, inbox does not exist or removed or emails from the sender are prohibited, etc.
Note: If an email service provider refused to accept email marking it as spam a critical error is saved. A sudden spike of errors may indicate that a campaign is being blocked by an email service provider.
More: How to avoid Spambox | campaign was blocked by email service provider
How to check which delivery error was indicated
Delivery log is saved into - System-Last delivery error.
Error log is a technical message from the subscriber's email service provider. There is no uniform text for all the providers. Different email service providers may have different reaction for one and the same error.
The main information may be obtained from smtp-error code. Common codes have 3 digits. Each digit corresponds to a certain information. Sendsay adds “-1” to an error code, if a system has an error “-1550” it corresponds to smpt error - “550”.
Each of the three digits has a specific information.
First digit corresponds to the delivery result:
4 – temporary error (errors 450, 451, 452 и т.д.)
5 – permanent fatal error (errors 500, 550, 551, 552, 553, 554, etc.)
The second and the third digits have specific information for the specialists.
450 Email is not available
550 Email is not available
554 Failed to transfer the data
How to get statistics on delivery errors
Delivery statistics can be checked for:
– a specific campaign,
– a specific period
– a specific subscribers group
Report contains details for :
– errors (most frequent errors),
– domains (which domains had most errors),
Detailed report can help you find which service blocked your campaign.
More: Campaign was blocked by email service provider