Shared folders disappear when I exit and then enter my email account

Shared folders disappear when I exit and then enter my email account

Hi 

I've been trying to share my email folders between accounts, but have not been able to do so successfully.

For instance, I can share an email folder from example1@fastgardener.com to example2@fastgardener.com and example2 can click accept and join the folder.

However when example2 logs out of his email account or refreshes the page, he loses access to the shared folder.

Can you explain why this is happening? And if there is any way to resolve this?
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Kind regards, Dan