If it was never received, then it was never delivered. If this is an IMAP account, the sent message will be in the sent folder on the server or in whichever folder you store sent items. If its a POP account, then sent items are getting stored locally only on the computer you sent it from. If you're not storing sent items, then it's nowhere to be retrieved.

You cannot recover any email you sent because it was sent. There are some occasions when it is possible such as if using an intranet connection within a business environment if the facility is setup by those controlling the internal email server or in some cases, the server deliberately has a time delay when you send an email, but you would still only have a very short time to recover it.

for example gmail webmail account can offer a time delay in it's webmail. But it only gives you up to 30 seconds max IF you dont click on anything else for those 30 seconds because all it really does is DELAY sending.

If email was never received and you are absolutely certain the recipients email address was correct, there are a couple of possible reasons. If the recipients mailbox was full at the time email was sent, you would usually get a bounce back email from server stating it could not be delivered. If the receiving server had a spam filter and most do, it is possible the server decided not to pass on to mailbox because it thought it was spam and simply removed the email; sometimes they refuse the email due to spam content and send the sender an email with error saying spam. The recipient may have received it but it went into server Junk/Spam mail box. If recipient uses 'Pop' then they would not see it as Pop accounts can only download from Inbox. They would need to check the webmail account asap because many servers auto empty Spam folders after x days.

It is worth checking the size of the email with attachment that you sent. Whilst your server may be able to send it, it might be too big for the recipient server to receive it. Please note that an email size increases due to conversion. It uses base64 encoding to convert binary into 7-bit ASCII. The base64 encoding adds up to 30% overhead. Meaning, a 20MB email (with attachment) becomes a 25MB email.

The document was a small spreadsheet with financial details. no formulas etc.. just a table I will check to see if receiver is using a pop email server. The final fix is to give the receiver a dropbox link to down load from or an email addy on our system as we will be sharing project files which would be better staying on our email server and email client. Yes it is IMAP server on my end but don't know yet about the recipient. The alternates are better solutions as it allows our control of the subject file .

Thank you both for your responses .. Yes I have the Sent file on my system but I really didn't want unauthorized 3rd parties to have the information sent and I should have protected the file Better. Bob

You have no control over the fate of that message at the receiving end once you have it sent on its way to the recipient, unless you have such access to the receiving account. I hope knowing so informs your future decisions.

... I really didn't want unauthorized 3rd parties to have the information sent ...

Unless the message was addressed incorrectly, it would be surprising for the message to be delivered to a third party. Some kind of "content filtering" would be a more likely explanation.