JavaMail not sending all emails

Question

Hello, I'm having an issue with JavaMail, that is kind of frustrating. i'm currently modifying a program that uses the javamail api to send errors and traces to clients if the program fails. The problem is that sometimes the emails don't send. The frustrating part is that some errors are emailed and some are not, even out of the same class, so this problem would seem to not be relegated to just a singular class.
I've enabled debugging and am not seeing anything relevant. My gut tells me that it has something to do with the subject(thought, I couldn't tell you what.)
I have debugged the code and everything is being submitted properly. The email just doesn't send.
Has anybody had this issue before?
Here's the debug trace...
DEBUG: JavaMail version 1.4ea
DEBUG: java.io.FileNotFoundException: C:\Program Files\Java\jdk1.5.0_11\jre\lib\javamail.providers (The system cannot find the file specified)
DEBUG: !anyLoaded
DEBUG: not loading resource: /META-INF/javamail.providers
DEBUG: successfully loaded resource: /META-INF/javamail.default.providers
DEBUG: Tables of loaded providers
DEBUG: Providers Listed By Class Name: {com.sun.mail.smtp.SMTPSSLTransport=javax.mail.Provider[TRANSPORT,smtps,com.sun.mail.smtp.SMTPSSLTransport,Sun Microsystems, Inc], com.sun.mail.smtp.SMTPTransport=javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc], com.sun.mail.imap.IMAPSSLStore=javax.mail.Provider[STORE,imaps,com.sun.mail.imap.IMAPSSLStore,Sun Microsystems, Inc], com.sun.mail.pop3.POP3SSLStore=javax.mail.Provider[STORE,pop3s,com.sun.mail.pop3.POP3SSLStore,Sun Microsystems, Inc], com.sun.mail.imap.IMAPStore=javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Sun Microsystems, Inc], com.sun.mail.pop3.POP3Store=javax.mail.Provider[STORE,pop3,com.sun.mail.pop3.POP3Store,Sun Microsystems, Inc]}
DEBUG: Providers Listed By Protocol: {imaps=javax.mail.Provider[STORE,imaps,com.sun.mail.imap.IMAPSSLStore,Sun Microsystems, Inc], imap=javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Sun Microsystems, Inc], smtps=javax.mail.Provider[TRANSPORT,smtps,com.sun.mail.smtp.SMTPSSLTransport,Sun Microsystems, Inc], pop3=javax.mail.Provider[STORE,pop3,com.sun.mail.pop3.POP3Store,Sun Microsystems, Inc], pop3s=javax.mail.Provider[STORE,pop3s,com.sun.mail.pop3.POP3SSLStore,Sun Microsystems, Inc], smtp=javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]}
DEBUG: successfully loaded resource: /META-INF/javamail.default.address.map
DEBUG: !anyLoaded
DEBUG: not loading resource: /META-INF/javamail.address.map
DEBUG: java.io.FileNotFoundException: C:\Program Files\Java\jdk1.5.0_11\jre\lib\javamail.address.map (The system cannot find the file specified)
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Sun Microsystems, Inc]
DEBUG SMTP: useEhlo true, useAuth false
DEBUG SMTP: trying to connect to host "mail.esagrp.com", port 25, isSSL false
220 esa20.esagrp.com Microsoft ESMTP MAIL Service, Version: 6.0.3790.3959 ready at  Mon, 1 Dec 2008 09:49:06 -0600
DEBUG SMTP: connected to host "mail.esagrp.com", port: 25
EHLO BPC
250-esa20.esagrp.com Hello [xxx.xxx.xx.xx]
250-TURN
250-SIZE
250-ETRN
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-8bitmime
250-BINARYMIME
250-CHUNKING
250-VRFY
250-X-EXPS GSSAPI NTLM
250-AUTH GSSAPI NTLM
250-X-LINK2STATE
250-XEXCH50
250 OK
DEBUG SMTP: Found extension "TURN", arg ""
DEBUG SMTP: Found extension "SIZE", arg ""
DEBUG SMTP: Found extension "ETRN", arg ""
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "DSN", arg ""
DEBUG SMTP: Found extension "ENHANCEDSTATUSCODES", arg ""
DEBUG SMTP: Found extension "8bitmime", arg ""
DEBUG SMTP: Found extension "BINARYMIME", arg ""
DEBUG SMTP: Found extension "CHUNKING", arg ""
DEBUG SMTP: Found extension "VRFY", arg ""
DEBUG SMTP: Found extension "X-EXPS", arg "GSSAPI NTLM"
DEBUG SMTP: Found extension "AUTH", arg "GSSAPI NTLM"
DEBUG SMTP: Found extension "X-LINK2STATE", arg ""
DEBUG SMTP: Found extension "XEXCH50", arg ""
DEBUG SMTP: Found extension "OK", arg ""
DEBUG SMTP: use8bit false
MAIL FROM:<[email protected]>
250 2.1.0 [email protected] OK
RCPT TO:<[email protected]>
250 2.1.5 [email protected]
DEBUG SMTP: Verified Addresses
DEBUG SMTP:   [email protected]
DATA
354 Start mail input; end with <CRLF>.<CRLF>
From: [email protected]
To: [email protected]
Message-ID: <[email protected]>
Subject: ONYX: Error occurred while trying to create a FileOutputStream. The
parameter is either not available, or can't be created.
MIME-Version: 1.0
Content-Type: multipart/mixed;
     boundary="----=_Part_0_10605044.1228146578495"
------=_Part_0_10605044.1228146578495
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
java.io.FileNotFoundException: c:\Shared\Quantum\archive\20081201\RateAccessRequest.xml (The system cannot find the path specified)
     at java.io.FileOutputStream.openAppend(Native Method)
     at java.io.FileOutputStream.<init>(FileOutputStream.java:177)
     at com.rates.xmlstructureobjects.SetAttributesAccessRequestDoc.<init>(SetAttributesAccessRequestDoc.java:49)
     at com.onyx.RatesInformation.<init>(RatesInformation.java:32)
     at com.onyx.testapp.main(testapp.java:55)
------=_Part_0_10605044.1228146578495--
250 2.6.0  <[email protected]> Queued mail for delivery
QUIT
221 2.0.0 esa.esagrp.com Service closing transmission channel

Answer 1

According to the trace, your mail server is accepting the message. If your mail server fails
to deliver the message to the recipient, you should check the logs in the mail server to see
what it's doing with the message.
It's possible that the sending mail server or the recipient's mail server has some sort of filter,
such as a spam filter, that's silently rejecting the message. If changing the content (or Subject
header) or the message causes it to be reliably delivered to the recipient, I'd look for some sort
of mail filter.