Mail clients need three ingredients: your email address, password, and hostname — typically your mail server hostname shown in cPanel or welcome documentation from HostStack.
IMAP keeps folders synchronized across devices; SMTP sends outbound mail. Prefer SSL/TLS ports supported by your exact cPanel stack — commonly993/465 or 587 — and avoid plaintext credentials on public Wi‑Fi.
If authentication fails, verify DNS MX records still point at HostStack mail routing before resetting passwords repeatedly.