I am unable to send attachment in Outlook. Problem started last evening. I attempted to send a jpg and pdf, and received an error code 554 6.6.0 Error sending message for delivery

Question

I received a png and pdf file last evening from a colleague. I downloaded the files, converted the png to a jpeg, send attempted to send two attachments to others. I received the following: 554.6.6.0 Error sending message for delivery. I sent the documents logging into my web-based account last evening, but I have been unable to send anything through my Windows Outlook email. Please provide some guidance.

Answer 1

The error code 554 6.6.0 you are encountering when trying to send attachments in Outlook typically indicates an issue with the message content or the attachment itself. Here are some steps you can take to troubleshoot and resolve the issue:

1. Check Attachment Size: Ensure that the total size of the attachments does not exceed the maximum limit set by your email provider. For Outlook on the web, the maximum attachment size is often around 10 MB. If your attachments exceed this limit, you will need to reduce their size or send them separately.
2. File Format Issues: Sometimes, specific file formats can cause issues. Ensure that the files you are trying to send (JPEG and PDF) are not corrupted. Try opening the files to confirm they are intact.
3. Transport Rules: If your organization has set up transport rules in Exchange, it may affect the delivery of messages. Check if there are any rules that might be causing the message to be deferred or rejected.
4. Password Protect Attachments: If the issue persists, try password-protecting the attachments before sending them. This can sometimes help bypass security filters that may be rejecting the message.
5. Send from Web-Based Account: Since you mentioned that you were able to send documents through your web-based account, consider using that method temporarily while troubleshooting the Outlook application.
6. Repair Outlook: If none of the above solutions work, consider repairing your Outlook application. This can resolve underlying issues that may be causing the error.

If the problem continues after trying these steps, it may be beneficial to contact your IT support team or check the Microsoft Community for additional assistance.

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References:

• "554 5.6.0 Invalid message content" when sending a message that contains an Excel or Word attachment
• Error when adding a large attachment in Outlook on the web

Answer 2

Hello,

Use the instruction here: https://support.microsoft.com/en-us/office/change-the-message-format-to-html-rich-text-format-or-plain-text-in-outlook-338a389d-11da-47fe-b693-cf41f792fefa#picktab=classic_outlook

Send it either using plain text or rich text, avoid using HTML, see if it goes through.