How Mac OS x includes attachments when replying to a message

When replying to an email using a mail app in Mac OS X, the default does not include attachments to the original message--doing so in most cases is not a problem. But when you copy or send an email to someone else, disappearing attachments may make you feel uncomfortable because the new recipients will find the attachments in the original message disappear and they will ask you to resend the attachment. For those long-span mail, sometimes because of the lack of attachments to make people confused.

To solve this problem is very simple. You can change the settings for the default forwarding attachment in the reply email setting, and you can, of course, set up a single mail session individually without affecting other messages. To do this, click on the "Edit" menu, select "Accessories" and tick "include original attachment in reply".

One thing you should be aware of is that the cost of appending an attachment to a mail session is to increase the bandwidth consumed by the message. Because although the attachments to the original message are already on the mail server, there is no caching mechanism to take advantage of this. If you use a slow Internet connection or use a mobile device to do hot spots, you should still turn this option off.

Another possible limitation is that some email providers limit the size of attachments, and if the limit is only 10 trillion or 25 trillion, then a few images and PDF files may exceed this limit. An oversized attachment can also cause the mail app to consume a large amount of system resources when previewing the attachment, which is especially noticeable on some older versions of the Mac. If your Mac gets very slow when previewing email attachments, you can turn off this feature by disabling the attachment preview, which will then use a file icon instead of the original preview feature when the attachment is disabled.