When you read the email with embedded images, Gmail displays an attachment icon, even if there are no attachments.

I tested this code:

Content HTML code in tmpHTML variable:

test

 

bye

Vb6 Code:

dim cid as string
cid = objSmtp.AddInline("C:\image.png")
tmpHTML = replace(tmpHTML , "C:\image.png", cid)
objSmtp.BodyText = tmpHTML

When I read the email I can see the images, it work. But I see also a Icon of attachments. Why?

And if I read the email in a Mac I see attachments. Why?

It is normal, embedded image is a type of attachment.
Even I use outlook or other popular email clients to send email with embedded images, both Gmail and Outlook.com displays attachment icon.