再起動して確認

• /etc/init.d/courier-authdaemon restart
• /etc/init.d/courier-imap restart
• telnetで確認できる。「AUTH=CRAM-MD5 AUTH=CRAM-SHA1 STARTTLS」の3項目を確認

 $ telnet localhost 143
 Trying 127.0.0.1...
 Connected to localhost.
 Escape character is '^]'.
 * OK [CAPABILITY IMAP4rev1 CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES AUTH=CRAM-MD5 AUTH=CRAM-SHA1 ACL ACL2=UNION STARTTLS] Courier-IMAP ready. Copyright 1998-2004 Double Precision, Inc.  See COPYING for distribution information.
 1 capability
 * CAPABILITY IMAP4rev1 CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES  AUTH=CRAM-MD5 AUTH=CRAM-SHA1 ACL ACL2=UNION STARTTLS
 1 OK CAPABILITY completed
 1 logout
 * BYE Courier-IMAP server shutting down
 1 OK LOGOUT completed
 Connection closed by foreign host.