The only problem here though is that the error mentioned here seems to have been a blank page rather than an email issue per se... The commons' server never attempted to send any messages to this user on that date.
I do see that we did send several messages to this user on December 21st, and from our POV they were received correctly. Is it possible for us to contact Patricia West and check if she received these messages from us on that day? I would bet she did.
/var/log/maillog-20111225:Dec 21 00:39:22 commons postfix/smtp[5516]: 7B2691746EC: to=<Patricia.West@lehman.cuny.edu>, relay=relay.gc.cuny.edu[172.29.28.89]:25, delay=0.23, delays=0.04/0.01/0.01/0.17, dsn=2.6.0, status=sent (250 2.6.0 <77d8b53d069526666f089cfc023c545f@commons.gc.cuny.edu> Queued mail for delivery)
/var/log/maillog-20111225:Dec 21 00:43:44 commons postfix/smtp[6632]: C5C7B1746DA: to=<Patricia.West@lehman.cuny.edu>, relay=relay.gc.cuny.edu[172.29.28.90]:25, delay=0.21, delays=0/0.02/0/0.19, dsn=2.6.0, status=sent (250 2.6.0 <d23ba10272fb301c82c0d918c0bc34a3@commons.gc.cuny.edu> Queued mail for delivery)
/var/log/maillog-20111225:Dec 21 09:27:12 commons postfix/smtp[4847]: EBD31174763: to=<Patricia.West@lehman.cuny.edu>, relay=relay.gc.cuny.edu[172.29.28.90]:25, delay=0.2, delays=0.03/0.01/0/0.15, dsn=2.6.0, status=sent (250 2.6.0 <38584abbafe4de1080119e147e2f127c@commons.gc.cuny.edu> Queued mail for delivery)
/var/log/maillog-20111225:Dec 21 09:57:24 commons postfix/smtp[10773]: EB83F1745D3: to=<Patricia.West@lehman.cuny.edu>, relay=relay.gc.cuny.edu[172.29.28.89]:25, delay=0.23, delays=0.02/0.01/0/0.2, dsn=2.6.0, status=sent (250 2.6.0 <a077a5eaf97383a02aa3598b61aeb3c4@commons.gc.cuny.edu> Queued mail for delivery)
/var/log/maillog-20111225:Dec 21 11:03:02 commons postfix/smtp[24275]: 7EF2F174790: to=<Patricia.West@lehman.cuny.edu>, relay=relay.gc.cuny.edu[172.29.28.89]:25, delay=0.22, delays=0.04/0.01/0.01/0.16, dsn=2.6.0, status=sent (250 2.6.0 <711728bbf99d2a71aecc21000a49227f@commons.gc.cuny.edu> Queued mail for delivery)
/var/log/maillog-20111225:Dec 21 11:19:55 commons postfix/smtp[27587]: 6195C1747C4: to=<Patricia.West@lehman.cuny.edu>, relay=relay.gc.cuny.edu[172.29.28.90]:25, delay=0.24, delays=0.04/0.01/0.01/0.19, dsn=2.6.0, status=sent (250 2.6.0 <e9afb61cdd12f841440f0789f10ab793@commons.gc.cuny.edu> Queued mail for delivery)
/var/log/maillog-20111225:Dec 21 12:00:12 commons postfix/smtp[3871]: CA15D1747C4: to=<Patricia.West@lehman.cuny.edu>, relay=relay.gc.cuny.edu[172.29.28.90]:25, delay=0.24, delays=0.04/0.01/0/0.19, dsn=2.6.0, status=sent (250 2.6.0 <e752e539e26efb67b13adf2467a18caf@commons.gc.cuny.edu> Queued mail for delivery)
/var/log/maillog-20111225:Dec 21 12:02:12 commons postfix/smtp[4167]: BCACC1747C4: to=<Patricia.West@lehman.cuny.edu>, relay=relay.gc.cuny.edu[172.29.28.89]:25, delay=0.2, delays=0.04/0.01/0/0.15, dsn=2.6.0, status=sent (250 2.6.0 <57c0160b0161d90ae34b0f07b1e389fa@commons.gc.cuny.edu> Queued mail for delivery)
/var/log/maillog-20111225:Dec 21 12:26:34 commons postfix/smtp[9628]: 4CBB91747C4: to=<Patricia.West@lehman.cuny.edu>, relay=relay.gc.cuny.edu[172.29.28.89]:25, delay=0.16, delays=0.04/0.01/0/0.11, dsn=2.6.0, status=sent (250 2.6.0 <a9d690dff8bf0499d10fc48438c61116@commons.gc.cuny.edu> Queued mail for delivery)