I found this in an email from logsentry:
Sep 22 11:31:24 dns4 sendmail[7629]: NOQUEUE: AS5300.PRI4.28.Dialup.Lahore.comsats.net.pk [210.56.17.155] (may be forged) did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Sep 22 11:31:51 dns4 sendmail[7649]: NOQUEUE: AS5300.PRI4.28.Dialup.Lahore.comsats.net.pk [210.56.17.155] (may be forged) did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Sep 22 11:31:51 dns4 sendmail[7653]: NOQUEUE: AS5300.PRI4.28.Dialup.Lahore.comsats.net.pk [210.56.17.155] (may be forged) did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Sep 22 11:31:57 dns4 sendmail[7650]: NOQUEUE: AS5300.PRI4.28.Dialup.Lahore.comsats.net.pk [210.56.17.155] (may be forged) did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Sep 22 11:31:58 dns4 sendmail[7651]: NOQUEUE: AS5300.PRI4.28.Dialup.Lahore.comsats.net.pk [210.56.17.155] (may be forged) did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA


and further down:
Sep 22 11:34:22 dns4 in.qpopper[7981]: EOF from at 210.56.17.155 (210.56.17.155): [0] 29 (Illegal seek); 0 (Success)
Sep 22 11:34:22 dns4 in.qpopper[7981]: (null) at 210.56.17.155 (210.56.17.155): -ERR POP EOF or I/O Error: 29 (Illegal seek); 0 (Success)
Sep 22 11:35:54 dns4 in.qpopper[8035]: EOF from at 210.56.17.155 (210.56.17.155): [0] 29 (Illegal seek); 0 (Success)
Sep 22 11:35:54 dns4 in.qpopper[8035]: (null) at 210.56.17.155 (210.56.17.155): -ERR POP EOF or I/O Error: 29 (Illegal seek); 0 (Success)
Sep 22 11:35:54 dns4 in.qpopper[8034]: EOF from at 210.56.17.155 (210.56.17.155): [0] 29 (Illegal seek); 0 (Success)
Sep 22 11:35:54 dns4 in.qpopper[8034]: (null) at 210.56.17.155 (210.56.17.155): -ERR POP EOF or I/O Error: 29 (Illegal seek); 0 (Success)
Sep 22 11:35:54 dns4 in.qpopper[8040]: EOF from at 210.56.17.155 (210.56.17.155): [0] 29 (Illegal seek); 0 (Success)
Sep 22 11:35:54 dns4 in.qpopper[8040]: (null) at 210.56.17.155 (210.56.17.155): -ERR POP EOF or I/O Error: 29 (Illegal seek); 0 (Success)
Sep 22 11:35:54 dns4 in.qpopper[8041]: EOF from at 210.56.17.155 (210.56.17.155): [0] 29 (Illegal seek); 0 (Success)
Sep 22 11:35:54 dns4 in.qpopper[8041]: (null) at 210.56.17.155 (210.56.17.155): -ERR POP EOF or I/O Error: 29 (Illegal seek); 0 (Success)
Sep 22 11:35:54 dns4 in.qpopper[8042]: EOF from at 210.56.17.155 (210.56.17.155): [0] 29 (Illegal seek); 0 (Success)
Sep 22 11:35:54 dns4 in.qpopper[8043]: EOF from at 210.56.17.155 (210.56.17.155): [0] 29 (Illegal seek); 0 (Success)

Was I hacked or was this a DOS?