Test email exception

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Hi everyone! I installed Passbolt on my AWS server, just to get stuck on the setup page, more precisely the email part.
I have an SMTP server at Namecheap that I use. I typed in the credentials, double-checked them, allowed ports 25 and 465 through the firewall, and it gave me this exception: Email could not be sent: Cake\Network\Socket::read(): Return value must be of type ?string, bool returned I also tested the email with swaks, and it worked perfectly.
Any help is appreciated!