OpenSSL
imap
openssl
can connect to an imap server and run commands (e.g. fastmail)
#!/usr/bin/env bash
{
sleep 3
echo "a1 LOGIN [email protected] myapppassword"
sleep 3
echo 'a1 LIST "" "*"'
sleep 3
} | openssl s_client -connect imap.fastmail.com:993 -crlf >/dev/null 2>&1