| Code |
Error Message |
Meaning |
Solution |
Glossary |
| 400 |
from parameter is missing |
The sender's email address is not provided |
Include the sender's email in the 'from' parameter |
'from' parameter: Sender's email address |
| 400 |
to parameter is missing |
The receiver's email address is not provided |
Include the receiver's email in the 'to' parameter |
'to' parameter: Receiver's email address |
| 400 |
message parameter is missing |
The email body is not provided |
Include the email body in the 'message' parameter |
'message' parameter: Email body |
| 400 |
‘message’ parameter is not a file |
The 'message' parameter is expected to be a file but isn't |
Provide the message as a file |
'message' parameter: Email body, in this case expected as a file |
| 400 |
Need at least one of ‘text’ or ‘html’ parameters specified |
Neither plain text nor HTML versions of the email are provided |
Include at least one of the 'text' or 'html' parameters |
'text'/'html' parameters: Plain text/HTML versions of the email |
| 400 |
Only one parameters ‘html’ or ‘template’ is allowed |
Both 'html' and 'template' parameters are provided, but only one is allowed |
Provide either the 'html' or 'template' parameter, not both |
'html'/'template' parameters: HTML version of the email / Template for the email |
| 400 |
Send options (parameters starting with o:, h:, or v:) are limited to 16 kB total |
The send options provided exceed the 16 kB limit |
Reduce the size of send options to less than 16 kB |
'o:', 'h:', 'v:' parameters: Send options for the email |
| 400 |
Too many recipients; max is 1000 |
The email is addressed to more than 1000 recipients |
Limit the number of recipients to 1000 or less |
Recipients: The individuals or groups receiving the email |
| 400 |
Header name must be pure ASCII: <header-name> |
The header name contains non-ASCII characters |
Use only ASCII characters in the header name |
ASCII: American Standard Code for Information Interchange, a character encoding standard |
| 400 |
<invalid-date> is not an RFC-2822 compliant date |
The provided date is not compliant with RFC-2822 |
Ensure the date is formatted according to RFC-2822 standards |
RFC-2822: Internet Message Format specification |
| 400 |
to parameter is not a valid address. please check documentation |
The receiver's email address is invalid |
Check and correct the format of the receiver's email address |
'to' parameter: Receiver's email address |
| 400 |
Invalid request content type. Expecting ‘multipart/form-data’ but got ‘application/x-www-form-urlencoded’ |
The content type of the request is not what is expected |
Change the request content type to 'multipart/form-data' |
'multipart/form-data': A type of HTTP request commonly used for file uploads |
| 400 |
malformed multipart/form-data request |
The 'multipart/form-data' request is formatted incorrectly |
Correct the format of the 'multipart/form-data' request |
'multipart/form-data': A type of HTTP request commonly used for file uploads |
| 400 |
unable to parse request: invalid URL escape |
The URL in the request contains invalid escape characters |
Correct the escape characters in the URL |
URL escape characters: Characters used in a URL to represent certain other characters |
| 400 |
unable to parse request: unexpected EOF |
The request ends unexpectedly |
Check the request for missing information or incorrect formatting |
EOF: End of File, in this case referring to the end of the request |
| 400 |
<time> invalid 24 hour time(value of ‘o:time-zone-localize’) |
The time provided is not in a valid 24-hour format |
Ensure the time is in a valid 24-hour format |
'o:time-zone-localize': A parameter for setting the time zone |
| 400 |
<time> is not a valid time to send (value of ‘o:time-zone-localize’) |
The specified time is not a valid time to send the email |
Choose a different, valid time to send the email |
'o:time-zone-localize': A parameter for setting the time zone |
| 400 |
invalid delivery time format |
The format of the delivery time is invalid |
Correct the format of the delivery time |
Delivery time: The time when the email should be delivered |
| 400 |
to parameter is not a valid address. please check documentation |
The receiver's email address is invalid |
Check and correct the format of the receiver's email address |
'to' parameter: Receiver's email address |
| 400 |
from parameter is not a valid address. please check documentation |
The sender's email address is invalid |
Check and correct the format of the sender's email address |
'from' parameter: Sender's email address |
| 400 |
cc parameter is not a valid address. please check documentation |
The CC email address is invalid |
Check and correct the format of the CC email address |
'cc' parameter: Carbon copy email address |
| 400 |
bcc parameter is not a valid address. please check documentation |
The BCC email address is invalid |
Check and correct the format of the BCC email address |
'bcc' parameter: Blind carbon copy email address |
| 400 |
‘recipient-variables’ parameter is not a valid JSON |
The 'recipient-variables' parameter is not correctly formatted as JSON |
Correct the format of the 'recipient-variables' parameter |
'recipient-variables' parameter: Variables specific to each recipient of the email |
| 400 |
Domain example.com is not allowed to send: Sandbox subdomains are for test purposes only. Please add your own domain or add the address to authorized recipients in Account Settings. |
The sender's domain is a sandbox subdomain, which are for testing only |
Use a non-sandbox domain, or add the recipient to the list of authorized recipients |
Sandbox domain: A domain for testing purposes |
| 400 |
Domain example.com is not allowed to send: Free accounts are for test purposes only. Please upgrade or add the address to authorized recipients in Account Settings. |
The sender's account is a free account, which is for testing only |
Upgrade to a paid account, or add the recipient to the list of authorized recipients |
Free account: An account that doesn't require payment |
| 400 |
Domain example.com is not allowed to send: The domain is unverified and requires DNS configuration. Log in to your control panel to view required DNS records. |
The sender's domain is unverified and needs DNS configuration |
Verify the domain and configure the DNS as needed |
DNS: Domain Name System, a system for translating domain names to IP addresses |
| 400 |
Domain example.com is not allowed to send: Please activate your Mailgun account. Check your inbox or log in to your control panel to resend the activation email. |
The sender's Mailgun account is not activated |
Activate the Mailgun account by following the instructions in the activation email |
Mailgun: A service for sending, receiving and tracking emails |
| 400 |
is not a valid secondary dkim domain name |
The provided secondary DKIM domain name is invalid |
Check and correct the format of the secondary DKIM domain name |
DKIM: DomainKeys Identified Mail, a method for verifying the authenticity of email senders |
| 401 |
Forbidden |
The user does not have the necessary permissions for the request |
Ensure the user has the correct permissions for the request |
Forbidden: A status code indicating the user doesn't have necessary permissions |
| 404 |
Domain not found: example.com |
The specified domain does not exist |
Use a valid, existing domain |
Domain: The part of an email address after the @ symbol |
| 403 |
Domain example is not allowed to send large batches yet |
The specified domain is not authorized to send large batches of emails |
Request permission to send large batches, or send smaller batches |
Batch: A group of emails sent as part of a single operation |
| 403 |
Rejected: IP <id-address> can’t be used to send the message |
The IP address of the sender is not allowed to send the message |
Use a different, authorized IP address to send the message |
IP address: A unique identifier for devices on a network |
| 413 |
request size exceeds 52.4MiB limit |
The size of the request exceeds the limit of 52.4MiB |
Reduce the size of the request to under 52.4MiB |
MiB: Mebibyte, a unit of digital storage |
| 429 |
Domain example.com is not allowed to send: request limit exceeded, try again after Mon, 20 Dec 2021 20:33:21 UTC |
The sender's domain has exceeded the limit for sending requests |
Wait until the specified time, then try sending the request again |
Request limit: The maximum number of requests that can be sent in a given time period |
| 429 |
Domain example.com is not allowed to send: bytes limit exceeded, try again after Mon, 20 Dec 2021 20:33:21 UTC |
The sender's domain has exceeded the limit for sending bytes |
Wait until the specified time, then try sending the request again |
Bytes limit: The maximum amount of data that can be sent in a given time period |
| 429 |
Domain example.com is not allowed to send: recipient limit exceeded, try again after Mon, 20 Dec 2021 20:33:21 UTC |
The sender's domain has exceeded the limit for number of recipients |
Wait until the specified time, then try sending the request again |
Recipient limit: The maximum number of recipients that can be addressed in a given time period |
| 500 |
Internal Server Error |
There is a problem with the server |
Wait and try the request again later, or contact the server administrator |
Internal Server Error: A general-purpose status code indicating a problem with the server |
