Username: This will be your full email address
Password: Your actual password
Hostname: mail.<your.domain> OR mail.callistodigital.co
IMAP - 143 (non-SSL), 993 (SSL)
POP3 - 110 (non-SSL), 995 (SSL)
SMTP - 25 (non-SSL), 465 (SSL), 587 (STARTTLS)
Under normal conditions you would set your e-mail client to use SSL with port 993 for IMAP, and port 465 for SMTP.
If your email app warns that the SSL certificate could not be validated, that is normal. Simply click to accept the certificate as valid.