cPanel uses following email ports:
IMAP (regular): 143
IMAP (TLS/SSL): 993
POP3 (regular): 110
POP3 (TLS/SSL): 995
SMTP (regular): 2525
SMTP (TLS/SSL): 465
Please login with complete username@domain.com and password. If you use SMTP, please check "SMTP Authentication RFC-2554". Do not check "require secure authentication".
If your username/password not accepted, please login to Webmail then verify username/password there. You can access webmail by typing /webmail after your domain name. For example, nyhost.org/webmail
If password not accepted within Webmail, please reset it via cPanel > Mail > select email account > manage > New password. Do not use own passwords, please consider cPanel password generator tool (simply click "generate" then copy strong password in safe place on local PC).