BACKGROUND
I am using MS Outlook for personal correspondence on my home computer from the stand alone version of MS Office 2019 (NOT Office 365, not cloud-hosted). I am the only user. I send and receive mail from

• an email address provided by my ISP
• a couple of email addresses associated with one of my domains
• a couple of email addresses associated with my other domain

For many years, these all worked together seamlessly in every version of Outlook that I used. (Version 2019 was the last one I purchased before I retired). I have moved the websites to different servers hosted by different companies several times, but never had multiple data files turn up in Outlook before (with or without messages in them).


PROBLEM
I now have several different data files that serve no purpose and I don't ever remember creating them:

• One is named for the email address issued by my ISP. Apparently it is not being used. Messages that I send and receive with this account appear in the Inbox and Sent Items folders in the main data file. I'd like to remove the unused data file named for this email address safely, without disturbing anything else.
  
• The second is named for an email address that I created but never used. I deleted the account from the host, so it no longer exists as a valid email address, but the data file is still in Outlook and I can't seem to get rid of it.
  
  
  
• The third is for my main email address. Email messages that I send from it appear under "Sent" in this data file and I have to drag each one of them to "Sent" in the main data file to keep them with my other correspondence. Paradoxically, incoming messages to this address appear where they should (in the main data file) and not under the data file named for this email address.

BOTTOM LINE
I want to get back what I originally had -- i.e. all email addresses using the same main data file, as they once did -- and to remove all the data files that aren't being used. I want to do this in the simplest and safest possible way. (Preferably, a method that is reversable, if I make a mistake). Any ideas? Thanks.

-- For the PSTs that are no longer being used.

Remove (Close)
Open and close Outlook Data Files (.pst) - Microsoft Support

This does not delete the PSTs from your computer (you can add them back to Outlook if needed), and Outlook won't let you Remove a PST that is the Default for an email account.

-- For the third file.

If you do File > Info > Account Settings > Account Settings and pick the "Email" tab and the account, it should show you where new mail is delivered and what the default "Send From" account is. What do you see that doesn't look right?

Thanks. I was able to close two of the data files. I am unsure of what you are suggesting that I do about the third one. I just want messages sent from the third email address to appear under Sent in the default file and not have to keep this other data file open.

If I follow your directions and go to File>Infor>Account Settings and pick the "Email" tab, I can see that it is using a different data file (though in practice it seems to be using that file's Sent box only). If I try to change the Delivery Email Location, the only options I see are the Inbox for the current file (though Outlook is actually delivering them to the default file's Inbox) and no option to pick the only other data file displayed (which apparently is called "Data File").

Not sure what to do with this, other than change it to Data File and see what happens.

My mistake. I was not clear on what info I wanted. Let's try a different approach.

Do I understand correctly - At this point the only remaining problem is that Sent items are showing up in the wrong place? If so, please check the following:

What are your settings for the "Save Messages" options?
Change where sent email messages are saved - Microsoft Support

What are your settings for the "Send Messages" options?
Change the account used to send email messages - Microsoft Support

"At this point the only remaining problem is that Sent items are showing up in the wrong place? " - That is correct. They are showing up under a different data file (and they are apparently the ONLY things in that data file.)

On my version of Outlook (the one that is part of the stand alone, desktop version of Office 2019 in the U.S.), if I follow the directions in the article you cite, I only get options for saving Drafts of messages before they are sent. Mine appear AFTER the message has been sent, under Sent, in a data file that appears to exist only for them to have a place to go. I still haven't be able to figure out how to make them appear in the one and only Data file that I am now using.

The one thing I haven't tried is closing that whole data file and just hoping it will go to the only one left open. But I'd feel more comfortable doing that if someone has already tried this and can confirm that it will work.

Thanks.

On my version of Outlook (Office 2019 if I follow the directions in the article you cite, I only get options for saving Drafts

I don't have Outlook 2019, so I can't verify, but both articles have, under "Applies To" at the top of the page:

So I'm not sure where we went off the script.

The setting I'm most interested in is "Change the account used to send email messages".
Change the account used to send email messages - Microsoft Support

My guess at this point is that you are Sending from an account other than your "Main" one.

If you do File > Account Settings > Account Settings, on the "Email" tab, is there more than one account? If so, which one is marked with the Default?

If you do File > Options > Mail. Under "Send Messages", is there a checkbox for "Always use the default account when composing new messages"? And is it checked?

Let me try to describe this situation better.

Imagine only two email accounts in Outlook:
Me@primary.com (default)
Me@secondary.com

Keep in mind that I created one and only data file in Outlook (primary.com)
Outlook generated a second data file on its own (secondary.com)

If I send a message from Me@primary.com to Me@secondary.com
- The message appears under Inbox for the primary.com data file
- A copy of the message appears under Sent in the primary.com data file.
- The message does not appear anywhere in the secondary.com data file

If I send a message from Me@secondary.com to Me@primary.com
- The message appears under Inbox for the primary.com data file
- A copy of the message appears under Sent in the secondary.com data file
- The message does NOT appear under Sent in the primary.com

I am not sure how your suggestions apply to remedying this particular situation.

Thanks.

All I can figure is that you are using POP3 accounts and you used to have both of them using the same PST file. But when you did the most recent setup you didn't tell Outlook that secondary.com should use the same PST file as primary.com.

If this is the case, you should be able to either "Change Folder" for secondary.com or remove and re-add it and tell Outlook to use "Existing Outlook Data File" as described in

Deliver All POP3 Accounts to One Outlook Inbox | Slipstick Systems

And the "Change the PST file after adding the account" and "Add the Account using Mail Setup dialog" sections of
Manually add POP or IMAP accounts to Outlook | Slipstick Systems

That's it! Thanks.

All my accounts were using the same PST file. I am not sure how the others were created (certainly not intentionally if I did so.)