Hi @techcoor ,
What's the type of your account(pop,imap or exchange)? Please first understand that recall function could only work for those exchange accounts in the same Exchange server.
There are also many other reasons that would cause recall failure, for more information, please refer to this article: Recall or replace an email message that you sent .If you don’t meet the restrictions and the email recall fails, under normal circumstances, each recipient would send a recall receipt, so whether your recalling messages was sent to multiple recipients?
Also, based on my research, I found a similar thread that mentioned we may receive multiple recall failure messages when we try to recall with imap account, and it says changing the track setting in recipients' client may work, if that's also your case, please kindly check if it could also work for you.
If the issue still exists, in order to avoid the interference of your corrupted outlook data file, it's also suggested to repair data file to check.
If it's still invalid or that's not your case, please provide us more information about your issue.
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