Unsolicited message diverting communications processor

• US 7,716,351 B1
• Filed: 01/20/2004
• Issued: 05/11/2010
• Est. Priority Date: 09/09/2002
• Status: Expired due to Fees

• Current Assignee: Engage Technology
• Original Assignee: Engage Technology
• Inventors: Huang, Alan, Lu, Haw-minn, White, Richard Paul, Spivack, Ira Victor
• Primary Examiner(s): Kang; Paul H
• Application Number:
  US10/761,864
• Time in Patent Office: 2,303 Days
• Field of Search: 709/225, 709/229, 709/245
• US Class Current: 709/229
• CPC Class Codes: H04L 51/212 using filtering or selective blocking

Abstract

The spam blocker monitors the SMTP/TCP/IP conversation between a sending message transfer agent MTA_—0 and a receiving message transfer agent MTA_—1; catches MTA_—0'"'"'s IP address IP_—0, MTA_—0'"'"'s declared domain D_—0, from-address A_—0; and to-address A_—1; and uses this source and content based information to test for unsolicited messages. It interrupts the conversation when MTA_—0 sends a RCPT command and uses the various test results to decide if the message is suspected of being unsolicited.

If the message is suspected of being unsolicited and to-address is not in the save_spam database then the spam blocker logs the rejected message, sends an error reply to MTA_—0 which forces MTA_—0 to terminate the connection before the body of the message is transmitted. If the message is suspected of being unsolicited and to-address is in the save_spam database then the spam blocker logs the rejected message, substitutes a diversion address A′_—1 for the to-address A_—1 in the RCPT command, and send the modified RCPT command to MTA_—1 and allows the conversation to continue. If the message is not suspected of being unsolicited then the spam blocker logs the allowed message, releases the intercepted RCPT command which allows the conversation to continue.

Claims

1. A networked computer comprising an unsolicited message diverting communications processor connected between mail transfer agents MTA_0 with an Internet address IP_0, a from-address A_0, a declared domain D_0, and a real domain DD_0, and MTA_1 with an Internet address IP_1, a domain D_1, a to-address A_1, a diversion address A′

_1, and a save_spam database, the unsolicited message diverting communications processor comprising;

a) monitoring means for monitoring the communications between MTA_0 and MTA_1;

b) determining means for determining if the communications contains an unsolicited message; and

c) intercepting means for intercepting a RCPT reply from MTA_0, substituting the diversion address A′

_1 for the to-address A_1 in the RCPT reply and sending a modified RCPT reply to MTA_1 if the message is determined to be unsolicited and if the to-address A_1 is in the save_spam database;

wherein the unsolicited message diverting communications processor does not intercept communications between MTA_0 and MTA_1 before a RCPT command from MTA_0 is received by the unsolicited message diverting communications processor, and

wherein the connection with MTA_0 is rejected before the data portion of the unsolicited message is transmitted.

2. The networked computer in claim 1, further includes an allow_address database and wherein the determining means determines if a message is not unsolicited by checking if the IP_0 is in the allow_address database.

3. The networked computer in claim 1, further includes a prevent_address database and wherein the determining means determines if a message is unsolicited by checking if IP_0 is in the prevent_address database.

4. The networked computer in claim 1, further includes access to an open relay database and wherein the determining means determines if a message is unsolicited by checking if IP_0 is in the open relay database.

5. The networked computer in claim 1, further includes access to a DNS (domain name server) database and wherein the determining means determines if a message is unsolicited by checking if IP_0 has a domain name entry DD_0 in the DNS database.

6. The networked computer in claim 1, further includes a bad_from database and wherein the determining means determines if a message is unsolicited by checking if the from-address A_0 is in the bad_from database.

7. The networked computer in claim 1, further includes a suspect_domain database and wherein the determining means determines if a message is unsolicited by checking if the real domain DD_0 matches the domain of the from-address A_0 and the domain of the from-address A_0 is in the suspect_domain database.

8. The networked computer in claim 1, wherein the determining means determines if a message is unsolicited by checking if the from-address A_0 matches the to-address A_1.

9. The networked computer in claim 1, wherein the determining means determines if a message is unsolicited by checking if the declared domain D_0 of MTA_0 is the same as the domain D_1 of MTA_1.

10. The networked computer in claim 1, wherein the determining means determines if a message is unsolicited by checking if the declared domain D_0 of MTA_0 does not match the real domain DD_1DD_0 and the declared domain D_0 is in the suspect_domain database.

11. The networked computer in claim 1, further includes a no_filter database and wherein the determining means determines if an unsolicited message should be blocked by checking if the to-address A_1 is in the no_filter database.

12. The networked computer in claim 1, further includes a rejected_connection database which logs the time, from-address A_0, to-address A_1, and the reason for the rejection if a message is rejected if the message is determined to be unsolicited.

13. The networked computer in claim 1, further includes an allowed_connection database which logs the time and to-address A_1 if the message is determined not to be unsolicited.

14. A method implemented in a networked computer for a receiving networked computer system with an Internet connection, a mail transfer agent MTA_1, an Internet address IP_1, a to-address A_1, a diversion address A′

_1, a save_spam database and an operating system capable of executing the method to divert unsolicited messages from a transmitting networked computer system with an Internet connection and a mail transfer agent MTA_0, an Internet address IP_0, a from-address A_0, a declared domain D_0, and a real domain DD_0 comprising the steps of;

a) waiting for a new SMTP connection request;

b) relaying and monitoring the replies from MTA_0 to MTA_1;

c) relaying replies from MTA_1 to MTA_0;

d) intercepting a RCPT reply from MTA_0 to MTA_1;

e) determining if the message is unsolicited by analyzing the monitored replies;

f) releasing the intercepted RCPT reply if the message is determined not to be unsolicited; and

g) substituting the diversion address A′

_1 for the to-address A_1 in the RCPT reply and sending the modified reply to MTA_1 if the message is determined to be unsolicited and if the to-address A_1 is in the save_spam database;

whereby MTA_1 controls the interaction between MTA_0 and MTA_1 before a RCPT command from MTA_0 is received and whereby the connection with MTA_0 is rejected before the data portion of the unsolicited message is transmitted.

15. A method implemented in a networked computer system for a receiving networked computer system with an Internet connection, a mail transfer agent MTA_1, an IP address IP_1, a domain name D_1, a to-address, A_1, a recipient diversion address A′

_1, an allow_address database, a prevent_address database, a suspect_domain database, a bad_from database, a no_filter database, a rejected_connection database, an allowed_connection database, a save_spam database, a diversion database, and an operating system capable of executing the method to divert unsolicited messages from a transmitting networked computer system with an Internet connection, a mail transfer agent MTA_0, an IP address of IP_0, a declared domain name D_0, a real domain name DD_0, and a from-address of A_0 comprising the steps of;

a) waiting for a SMTP connection request on the receiving networked computer system'"'"'s Internet connection;

b) sending a 220 reply to MTA_0 to acknowledge the requested SMTP connection request;

c) extracting IP_0 from the SMTP connection request;

d) requesting the real domain name DD_0 for IP_0 from a DNS database;

e) testing if the real domain name DD_0 is “

no name”

;

f) testing if IP_0 is in an open relay database;

g) testing if IP_0 is in the allow_address database;

h) testing if IP_0 is in the prevent_address database,

i) requesting a connection with MTA_1;

j) waiting for a 220 reply from MTA_1 to acknowledge the requested connection;

k) waiting for a reply from either MTA_0 or MTA_1;

l) jumping to step o) if the reply is not from MTA_1;

m) relaying the reply from MTA_1 to MTA_0;

n) jumping to step k) to wait for a new reply;

o) jumping to step u) if the reply from MTA_0 is not a HELO;

p) extracting the declared domain name D_0 from the reply;

q) testing if the declared domain name D_0 is the same as D_1;

r) testing if the declared domain name D_0 of MTA_0 does not match the real domain name DD_0 of MTA_0 AND the declared domain name D_0 of MTA_0 is in the suspect_domain database;

s) relaying the HELO reply from MTA_0 to MTA_1;

t) jumping to step k) to wait for a new reply;

u) jumping to step aa) if reply from MTA_0 is not a MAIL;

v) extracting the from-address A_0;

w) testing if A_0 is in the bad_from database;

x) testing if DD_0 does not match the domain of A_0 and the domain of A_0 is in the suspect_domain database;

y) relaying MAIL reply to MTA_1;

z) jumping to step k) to wait for a new reply;

aa) jumping to step qq) if the reply from MTA_0 is not a RCPT;

bb) extracting the to-address A_1;

cc) testing if A_1 is in the no_filter database;

dd) testing if A_0 matches A_1;

ee) jumping to step nn) if t_allow OR t_no_filter OR NOT (t_prevent OR t_open OR t_DD_0 OR t_bad_from OR t_suspect_domain OR t_match);

ff) logging time, A_0, A_1, and reason for rejection in the rejected_connection database;

gg) jumping to step ll) if A_1 is not in the save_spam database;

hh) looking up A′

_1 in the diversion database;

ii) substituting A′

_1 for A_1 in the RCPT reply;

jj) sending the modified RCPT reply to MTA_1;

kk) jumping to step k) to wait for a new reply;

ll) rejecting the connection with MTA_0 connection by sending a 550 reply to MTA_0;

mm) jumping to step k) to wait for a new reply;

nn) logging time and A_1 in the allowed_connection database;

oo) relaying RCPT reply from MTA_0 to MTA_1;

pp) jumping to step k) to wait for a new reply;

qq) jumping to step bbb) if the reply from MTA_0 is not DATA;

rr) relaying DATA reply to MTA_1;

ss) waiting for a 354 reply from MTA_1;

tt) relaying the 354 reply from MTA_1 to MTA_0;

uu) waiting for the data from MTA_0;

vv) relaying the data from MTA_0 to MTA_1;

ww) waiting for a .\r\n from MTA_0;

xx) relaying the .\r\n from MTA_0 to MTA_1;

yy) waiting for a 250 reply from MTA_1;

zz) relaying the 250 reply to MTA_0;

aaa) jumping to step k) to wait for a new reply;

bbb) jumping to step eee) if reply from MTA_0 is not RSET, SEND, SCML, SAML, VRFY, NOOP, EXPN, HELP, or TURN;

ccc) relaying the reply to MTA_1;

ddd) jumping to step e) to wait for a new reply;

eee) jumping to step jjj) if the reply from MTA_0 is not a QUIT;

fff) relaying the QUIT reply to MTA_1;

ggg) waiting for a 221 reply from MTA_1;

hhh) relaying the 221 reply from MTA_1 to MTA_0;

iii) jumping to step a) to wait for a new connection;

jjj) sending a 500 reply to MTA_0 to signal a syntax error; and

kkk) jumping to step a) to wait for a new connection.