Apple Mac OS X Server (Administrator’s Guide) - Manual (Page 397)

Mail Service 397
Updating the DNS Cache in Mail Service
The mail service stores verified domain names in a cache and does not verify the cached
information unless you set the cache to be updated periodically. The cache improves mail
service performance, because the mail service doesn’t have to contact the DNS service for
every message. You may reduce mail service performance if you set the cache to be updated
too frequently.
To change how often the mail service updates its DNS cache:
1 In Server Settings, click the Internet tab.
2 Click Mail Service and choose Configure Host Settings.
3 Click the Network Settings tab.
4 Select one of the Cache Settings options.
Select “Cache DNS information for __ minutes” and enter the number of minutes you want
information to be stored before the cache is refreshed.
Select “Respect ‘Time to Live’ (TTL) DNS Settings” if you want to use the default settings of
the DNS service. Ordinarily, your mail service resends mail repeatedly until it makes a
connection with the server at the destination. TTL specifies how long your mail service
continues requesting connection information from DNS before giving up and generating a
nondelivery report.
5 Click Save.
Changing Mail Service Timeouts
If your mail service has frequent trouble remaining connected to another server, you can
increase the length of time your mail service waits before giving up on connections with
other servers. This can be helpful if your server has a slow or intermittent connection to
the Internet.
To change the allowed connection time:
1 In Server Settings, click the Internet tab.
2 Click Mail Service and choose Configure Host Settings.
3 Click the Network Settings tab.
4 In the Open Connection field, enter the number of seconds you want your mail service to
wait before giving up on a connection attempt.
5 In the Read/Write field, enter the number of seconds you want to allow the other mail host to
respond before your mail service stops attempting to send or receive a message.
6 Click Save.