[Dovecot] Can't download emails with large file attachment

[prabin]

Hi,
I am using CentOS 5.9 with postfix+dovecot v1.0.7
I have problem in downloading emails with attachment of more than 3MB 
via my email client. (Thunderbird, Outlook, etc) I can send emails out 
with more than 3MB without any problem, whereas i can't download emails.

Following are the errors i found on maillog
*dovecot: pop3-login: SSL_write() syscall failed: Bad file descriptor**
**dovecot: impa-login: SSL_write() syscall failed: Bad file descriptor*

After this the email client stops downloading emails.

What could be the problem ? Please help me fix this . Thank You

*
**dovecot version: dovecot-1.0.7-8.el5_9.1**
**openssl version: openssl-0.9.8e-26.el5_9.1**
**CentOS 5.9*
  dovecot: POP3(support1): Disconnected top=0/0, retr=1/0, del=0/17, 
size=57279820
*Sep 16 17:25:56 mail dovecot: pop3-login: SSL_write() syscall failed: 
Bad file descriptor [110.44.xx.xx]*


dovecot -n

# 1.0.7: /etc/dovecot.conf
log_timestamp: %Y-%m-%d %H:%M:%S
listen(default): 61.xx.xx.XX:143
listen(imap): 61.xx.xx.XX:143
listen(pop3): 61.xx.xx.XX:110
ssl_listen(default): 61.xx.xx.XX:993
ssl_listen(imap): 61.xx.xx.XX:993
ssl_listen(pop3): 61.xx.xx.XX:995
ssl_cert_file: /etc/pki/tls/certs/dovecot.pem
ssl_key_file: /etc/pki/tls/private/dovecot.pem
ssl_cipher_list: ALL:!LOW
verbose_ssl: yes
login_dir: /var/run/dovecot/login
login_executable(default): /usr/libexec/dovecot/imap-login
login_executable(imap): /usr/libexec/dovecot/imap-login
login_executable(pop3): /usr/libexec/dovecot/pop3-login
login_process_per_connection: no
login_process_size: 512
mail_location: maildir:~/Maildir
mail_executable(default): /usr/libexec/dovecot/imap
mail_executable(imap): /usr/libexec/dovecot/imap
mail_executable(pop3): /usr/libexec/dovecot/pop3
mail_plugin_dir(default): /usr/lib64/dovecot/imap
mail_plugin_dir(imap): /usr/lib64/dovecot/imap
mail_plugin_dir(pop3): /usr/lib64/dovecot/pop3
auth default:
   mechanisms: plain login
   verbose: yes
   debug: yes
   debug_passwords: yes
   passdb:
     driver: pam
   userdb:
     driver: passwd
   socket:
     type: listen
     client:
       path: /var/spool/postfix/private/auth
       mode: 432
       user: postfix
       group: postfix