Email attachments stripped off contents reducing to 0 bytes

Hy there.
Glad to know there is a community. I hope I am able to give back too in some way.
For now I have a problem with email attachments. I am not a developer. My website is installed on Windows.
All Emails are delivered perfectly by Gravity forms. However in case the Gravity form contains an upload field which is set to be sent as an attachment to the email - the email goes through but the attachment is stripped to 0 bytes and thus cannot be downloaded. I changed email providers and checked - its the same issue with gmail or Outlook. When I contacted outlook support they said it could be Antivirus or Browser issue. I changed browsers and paused the antivirus but yet the email attachment didnt get through.
So is there a specific setting needed on Windows so that the email provider does not strip the attachments. Is it only in my case that the email attachments are not being delivered or is there a different plugin needed. I use POST SMTP for emails - Does this Plugin not support sending attachments? - DO I have change the email plugin? Or is there something missing in Windows that the attachment does not get through? Why is the email provider stripping the attachment of its content? thanks