This issue is highly technical related to IT security and is not related to any accounting issues. I'm not sure most of the first layer support team and Intuit Community team is familiar with the terms spam filters, firewalls, endpoint security and more. You should send a private message to any Community Moderators to escalate this issue to their IT Security team and fix it immediately.
Otherwise, explore another accounting app and purchase a 3rd party conversion service if required.
