Strange backend condition

[abreaux]

We are seeing a strange error on our mtas where they will suddenly fail communications with the stores. An excerpt from the logs:

Sep 28 20:42:22 mta03 postfix/smtpd[8327]: disconnect from mail05.philasd.org[170.235.1.95]
Sep 28 20:42:22 mta03 postfix/smtpd[8326]: connect from mail05.philasd.org[170.235.1.95]
Sep 28 20:42:22 mta03 postfix/smtpd[8326]: disconnect from mail05.philasd.org[170.235.1.95]
Sep 28 20:42:22 mta03 postfix/smtpd[8325]: connect from mail05.philasd.org[170.235.1.95]
Sep 28 20:42:22 mta03 postfix/smtpd[8325]: disconnect from mail05.philasd.org[170.235.1.95]

This can happen for a long time, thousands of entries and then the condition sometimes goes away. It's been re-occuring at a high frequency. Running tcpdump during the event reveals an error in the LMTP conversation where the store indicated no valid recipients.

This occurs after the MAIL FROM: is sent by the mta, the store says OK, but the mta does not send RCPT TO: but instead sends DATA. Then the store responds with no valid recipients.

I'm thinking it's a malformed message but this is presumably happening after it's gotten through our mtas?

Thoughts/Ideas/Suggestions?

[abreaux]

So no one else is experiencing this??