Why eM Client will not open? Is the mail_data file too big?

O.S. Windows XP Professional Service Pack 3

My eM Client crashed while I was reading an e-mail and below is the message I get.
I went to check the eM client data and noticed the file “mail_data.dat” file is 4.1 Gb in size. Is it too big? Is that what cause the crash?? I cannot open mails any more.

System.Data.SQLite.SQLiteException: Insertion failed because the database is full
database or disk is full (main/70)
at System.Data.SQLite.SQLite3.Reset(SQLiteStatement stmt)
at System.Data.SQLite.SQLite3.Step(SQLiteStatement stmt)
at System.Data.SQLite.SQLiteDataReader.NextResult()
at System.Data.SQLite.SQLiteDataReader…ctor(SQLiteCommand cmd, CommandBehavior behave)
at System.Data.SQLite.SQLiteCommand.ExecuteReader(CommandBehavior behavior)
at System.Data.SQLite.SQLiteCommand.ExecuteNonQuery()
at System.Data.SQLite.SQLiteConnection.Open()
at DbRepair.DbTools.OpenConnection(String fileName)
at DbRepair.Form1.CheckCorruption()
at DbRepair.Form1.Check(Object state)

Please check your disk - it seems that there is no free space left.