Common Okta SendGrid SMTP Errors and Troubleshooting
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Overview
Simple Mail Transfer Protocol (SMTP) is a protocol used for sending and receiving email. When using SendGrid with Okta, administrators may encounter various SMTP response codes and bounce errors. Understanding these common error codes, such as 550, 551, 552, and 553, assists in troubleshooting email delivery failures.
Applies To
- Okta Identity Engine (OIE)
- Okta Classic Engine
- Simple Mail Transfer Protocol (SMTP)
- SendGrid
Solution
What is Simple Mail Transfer Protocol?
Simple Mail Transfer Protocol (SMTP) is a TCP/IP protocol used for sending and receiving email. Email clients, including Gmail, Outlook, Apple Mail, and Yahoo Mail, commonly use SMTP. An SMTP server is an application or computer that sends, receives, and relays email.
SMTP response codes indicate the status of an email delivery request.
Each SMTP call returns a response. Responses in the 200 range indicate success, while 400-level responses typically indicate deferrals. SendGrid continues to retry resending deferred messages for up to 72 hours. Responses in the 500 range indicate hard failures that the servers do not retry.
What are common SendGrid error messages and troubleshooting steps?
Review the following table to identify common SendGrid error codes, their associated error messages, and the corresponding troubleshooting actions required to resolve them.
| Error Code 550 | |
| Requested action not taken: Mailbox unavailable | You are temporarily blocked from sending emails due to repeated bad requests. |
| This error is caused when the user’s mailbox was unavailable. Usually, this is because it could not be found or because of incoming policy reasons. Remove the address(es) from the list - it may be fake, or it was mistyped. | Too many bad requests, such as bad sender or bad recipient address, have been sent in a short time frame. A temporary block of a few minutes has been activated to prevent more bad requests until a fix can be implemented. |
| Error Code 551 |
| User does not exist. |
| The intended mailbox does not exist on the recipient server. Remove the address(es) from the list. |
| Error Code 552 |
|
This message is larger than the current system limit or the recipient’s mailbox is full. |
| The recipient's mailbox has exceeded its storage limits. Messages are not resent with this error code because this is usually a sign this is an abandoned email. |
| Error Code 553 |
| Invalid/Inactive user |
| The message was refused because the mailbox name is either malformed or does not exist. Remove these addresses from the list. |
Less Common Error(s):
| Error Code 552 | |
| Mail refused | Delayed Bounce - Unable to Parse Server Reason |
| This is a default response that can be caused by a lot of issues. There is often a more readable portion of this error that gives more detailed information, but, if not, remove the address(es) from the list. | This is what SendGrid displays when the recipient's server returns a blank reason code. |
Keep in mind that this is only a short rundown of the most common errors and a quick definition of why these bounces happen
This guide on How to Unblock an Email Address From the Okta Email Address Bounce List via API may provide a better understanding on these errors and how they can be prevented.
