One of our users has a problem with the web interface search functionality - it only returns a few very old emails (from 2009) and no recent ones.

I tracked the issue down to convertd not running. I can see messages like this in the mailbox.log:

2012-10-30 10:14:46,809 INFO  [LmtpServer-795] [name=...;mid=10;ip=...;] HttpMethodDirector - I/O exception (java.net.ConnectException) caught when processing request: Connection refused 
2012-10-30 10:14:46,809 INFO  [LmtpServer-795] [name=...;mid=10;ip=...;] HttpMethodDirector - Retrying request 
2012-10-30 10:14:46,819 WARN  [LmtpServer-795] [name=...;mid=10;ip=...;] ParsedMessage - Unable to parse part=2.2.1 filename= content-type=text/rtf message-id= 

com.zimbra.cs.mime.MimeHandlerException: extraction failed
         at com.zimbra.cs.mime.handler.ConverterHandler.getContentImpl(ConverterHandler.java:108)
         at com.zimbra.cs.mime.MimeHandler.getContent(MimeHandler.java:157)
 Caused by: com.zimbra.cs.convert.ConversionException: connect failed
         ... 32 more
 Caused by: java.net.ConnectException: Connection refused
         at java.net.PlainSocketImpl.socketConnect(Native Method)
         at com.zimbra.cs.convert.ConverterClient.call(ConverterClient.java:108)
         at com.zimbra.cs.convert.ConverterClient.post(ConverterClient.java:138)
         at com.zimbra.cs.convert.ConverterClient.extract(ConverterClient.java:88)
         at com.zimbra.cs.mime.handler.ConverterHandler.getContentImpl(ConverterHandler.java:101)
         ... 31 more 

2012-10-30 10:14:46,828 WARN  [LmtpServer-795] [name=...;mid=10;ip=...;] ParsedMessage - Message had analysis errors in 1 parts (Message-Id: , Subject: ...) 
2012-10-30 10:14:46,828 INFO  [LmtpServer-795] [name=...;mid=10;ip=...;] index - Temporary error generating index data for item ID: 1226872. Indexing will be retried 

         at com.zimbra.cs.mailbox.Message.generateIndexData(Message.java:1208)
This breaks indexing new messages with attachments as well as reindexing mailboxes where it fails on the first message with attachment.

I tried to restart Zimbra (zmcontrol restart) as well as "zmstatctl start" that was suggested in some other thread but it didn't help.

What can I do to fix it?

We're running Release 7.2.0_GA_2669.RHEL5_64_20120410001942 CentOS5_64 NETWORK edition.