It turns out that the email application does not include the attachments in the original email by default, which causes the attachments in the email to disappear. The disappearance of attachments sometimes makes people unable to understand the meaning of the email. For example, if you send an email to your boss, but after the email is successfully sent, you find that the file you attached is not there, this will cause some trouble.

Solving this problem is extremely simple. You can change the settings for forwarding attachments by default in the reply email settings. Of course, you can also set it individually for a specific email conversation without affecting other emails. For specific operations, click the "Edit" menu, select "Attachments", and then check "Include original attachments in reply".

One thing you need to pay attention to is that appending attachments to an email conversation comes at the cost of increasing the bandwidth occupied by the email. Because although the attachment of the original email is already on the mail server, there is no caching mechanism to take advantage of this. If you're on a slower Internet connection or using your mobile device as a hotspot, you should still turn this option off.

Another possible limitation is that some email providers will limit the size of attachments. If the limit is only 10 MB or 25 MB, then several pictures and PDF files may exceed this limit. Attachments that are too large will also cause the mail application to consume a lot of system resources when previewing attachments. This situation is especially obvious on some older versions of Mac. If your Mac becomes slow when previewing email attachments, you can turn off this feature by disabling attachment preview. After disabling it, the attachment will use a file icon instead of the original preview function.

The above is the solution to the problem of attachments disappearing when replying to emails using the Mail application in Mac OS Set it up and it will make sending email easier and hassle-free.