Do you mean that when you try to email a file from within Excel, it doesn't automatically call TB and attach the file? Do you have the latest TB, 60.6.1? There have been some fixes for this type of operation.

The error message I get says "General mail failure" Quit Microsoft Excel, restart the mail system, and try again." I shut down my PC and did a restart. Is this what is meant by "do a restart?" How do I know which version I have? I know it is at least 60, but don't know if it is 60.6.1. Also of some interest is that yesterday I sent the spreadsheet to someone as a PDF and believe it was successful. The other person I am sending it to cannot accept a PDF version so, for years, I have always sent it as an email attachment. Please word your response as if I am an idiot.....I am not good at this stuff. Thank you.

'Restart the mail system' probably means to close and reopen your email program, but restarting the PC would accomplish the same thing.

Select Help/About Mozilla Thunderbird to see your version (press Alt key if the Menu Bar is hidden), then Check for Updates if it's not v. 60.6.1.

As a fallback, you can always save the document from Excel and then attach it to a TB message like any other attachment.

Yes, I do have 60.6.1 Not sure what you mean by "as a fallback....." That is precisely what I always have done but no longer can and what this question is about! Am I not understanding something you're telling me? Thank you.

The method I guessed you were using was to initiate the sending of the Excel document from within Excel. The fallback adds a few more steps: you save the file in Excel, start a new message in TB, then attach the file, all while Excel is closed or in the background. But if you can't even attach files to a message, assuming they are not too large, it suggests there is some security or antivirus program interrupting the process. Do you have an AV program scanning outgoing mail? If so, disable that option and see if it helps.

If Excel is closed, what am I supposed to save the file to so I can attach it to a TB email? I have Webroot..are you telling me to disable that also?

When the file is open in Excel, save it to a location such as Documents or Desktop, then in a new TB message, click the Attach icon and select the saved file.

It appears Webroot doesn't scan emails, so it's probably not a factor.

OMG!! It worked! Thank you thank you!