Problems Recieving Mail From Domain

Hey Guys,

We've suddenly started having problem receiving mail from one of our sister school districts. I'm trying to figure out if it's us or if it's them. All I can find in the log related to their domain are entries like this:

Code:

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Apr 29 13:26:42 cottontail postfix/smtpd[23956]: connect from le-m600.llesd.k12.ca.us[149.20.82.5]
Apr 29 13:26:42 cottontail postfix/smtpd[23956]: lost connection after EHLO from le-m600.llesd.k12.ca.us[149.20.82.5]
Apr 29 13:26:42 cottontail postfix/smtpd[23956]: disconnect from le-m600.llesd.k12.ca.us[149.20.82.5]
Apr 29 14:30:07 cottontail postfix/smtpd[26091]: connect from le-m600.llesd.k12.ca.us[149.20.82.5]
Apr 29 14:30:07 cottontail postfix/smtpd[26091]: lost connection after EHLO from le-m600.llesd.k12.ca.us[149.20.82.5]
Apr 29 14:30:07 cottontail postfix/smtpd[26091]: disconnect from le-m600.llesd.k12.ca.us[149.20.82.5]
Apr 29 14:30:08 cottontail postfix/smtpd[20215]: connect from le-m600.llesd.k12.ca.us[149.20.82.5]
Apr 29 14:30:08 cottontail postfix/smtpd[20215]: lost connection after EHLO from le-m600.llesd.k12.ca.us[149.20.82.5]
Apr 29 14:30:08 cottontail postfix/smtpd[20215]: disconnect from le-m600.llesd.k12.ca.us[149.20.82.5]

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Is there anywhere I can look that'll give me more details on how/why the connection was lost?

Any help would be much appreciated!

If it helps any, their mail server reports

Code:

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----- The following addresses had transient delivery errors -----

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in the bounce their users recieve when sending us e-mail. We can't seem to get any more details from them other than that, unfortunately.

I'm not sure what "transient deliver errors" are!