Hi,
I think the issue is caused by the "Embed images in emails" option in the HikaShop configuration. When this option is enabled, HikaShop converts image URLs in the email body to local file paths in order to embed them as attachments. However, if the image URLs in your email used a different format than your site URL (for example
www.cancunflowershop.com.mx
vs cancunflowershop.com.mx, or http vs https), the conversion would fail and PHPMailer would report "Could not access file" because it was trying to open a full URL as a local file path.
We've updated the code so that it now correctly resolves image URLs regardless of whether they use http or https, and with or without the www prefix.
Please download the latest build of HikaShop 6.3.0 from your account and install it over your current version. It should fix the issue.