4 Common Reasons and Solutions for Failure to Send Emails

4 Common Reasons and Solutions for Failure to Send Emails There is a small list of 4 common reasons for failure to send emails below, and you can find the solution for each issue.

Error Code List and Solutions

550 Invalid User: The user is invalid and the email address cannot be found. Some mailboxes think that you are sending a spam mailbox and also return this message.
Solution: Check and modify the email content and try again. If it still doesn't work, delete the invalid email address.

550 User is locked: the SMTP client function is not activated.
Solution: The mailbox provider generally provides an activation method, search online or contact the mailbox provider to activate.

4.x.2 Too many messages for this session: Send too many messages at once.
Solution: Use the sending strategy and reduce the sending speed.

5.4.5 Daily sending quota exceeded: The sending limit of today is exceeded.
Solution: Send after 24 hours.

Didn't find the error code of your email delivery failure? For more information, please read 14 Reasons and Solutions for Email Delivery Failure and Return Messages.

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