Brute force attack from my IP

My ip gets blacklisted everyday F***day by hostgator, soon as i get home and connect my laptop to the internet failed logins start coming to my IMAP emails accounts and IP gets into blacklist for several hours. Setting on Airmail configured correctly and works fine during a day. Hostgator support cant help and keep saying its " Brute force attack" check for malware or mail client configuration . ( no malware deeply scanned and same things happening from new laptop )
Any thought where to look to fix this issue ?