If you are not able to find your important work emails or have accidentally deleted the email, you need not to worry and need not go into a panicking state. It can be the case that emails are in unexpected folders like Spam or trash from where you can easily recover deleted yahoo emails.
It happens that when the same mail is sent to more than one recipient, it is automatically sent to the Spam folder. Thus, you can look for the required mail there.
If you have mistakenly deleted the email, before permanent deletion the email goes to the Trash folder. By opening the Trash, locate your email there and recover it by clicking the “Restore” button.
It is very inarticulate to mention that if you are expecting an email but not getting it or unable to find it in the inbox, it can be due to Yahoo Email Is Not Loading On Firefox may be because of a poor connection or a Yahoo mail server problem.
So, you should wait for some time and see if the mail arrives, otherwise, if you are sure that your mail is deleted then you can write an email to the Yahoo support service to recover deleted yahoo emails.
Also, if you are expecting to receive an email from an unknown source, then the SMTP protocol will automatically block the user or delete the mail to prevent any malicious activity. Thus, you should ensure that you are using the right yahoo SMTP server settings, in which, the server is smtp.mail.yahoo.com, port number is 465 or 587 and encrypted connection is SSL.