We've built a custom email signature to use within Office 365, however, when I send a test to a Gmail account, 2 of the 9 images show as attachments. Does anyone know how I can prevent this from happening? Below is a snippet:

<table style="width: 480px; font-size: 9pt; font-family: Arial, sans-serif; line-height:14px; " cellpadding="0" cellspacing="0">
        <td style="width:125px; vertical-align: middle" valign="middle" align="center">
            <a target="_blank" href="https://www.google.co.uk">
                <img border="0" width="88" height="88" style="width:88px; height:88px; border:0;" src="my-image-url.png" alt="Example Logo">

Images appear in Gmail as image001.png image006.png.

Any help would be great, thanks.