Inbox Emails from user account missing Help!

Hello all, This morning a account lost all inbox emails i checked the log if some Login with POP3 was the cause but nothing.... but i have this error, is releated to the missing emails? Oct 28 10:43:01 s1 dovecot: lmtp(7409): Error: lmtp-server: conn unix:pid=7538,u id=47 [2]: rcpt joana.sousa@bystart.com: Mailbox INBOX: write(/home/bystart/mail /bystart.com/joana.sousa/dovecot-uidlist.tmp) failed: No space left on device Oct 28 10:43:32 s1 dovecot: lmtp(joana.sousa@bystart.com)<7409><2FckAVTGtl3xHAAA jiTuQQ>: Error: lmtp-server: conn unix:pid=7601,uid=47 [3]: rcpt joana.sousa@bys tart.com: Mailbox INBOX: Saving mail: save: write(/home/bystart/mail/bystart.com /joana.sousa/tmp/1572259412.M26005P7409.s1.bystart.com) failed: No space left on device
We have all the emails in sendind folder, is like 350mb but on used space shows 1.2GB? pls help me. thanks