Cache DNS Results

If this option is selected, the server verifies domain names in outgoing mail against your network's DNS server, stores the results, and does not verify the domain name again. Since the DNS database doesn't change frequently, caching can improve performance.

Respect Time to Live (TTL) DNS Settings:
Select this to cache DNS results for the recommended times.

Cache DNS information for __ minutes:
Enter a number to specify how long DNS results are cached.

Check DNS Before Connecting

If this option is selected, the server polls the DNS server before every connection. This option is more reliable because cached DNS information might be out of date.

DNS Request

You can choose the information the mail server requests from the DNS server:

•	MX-List and A-Record
•	MX-List only
•	A-Record only

Network Timeout

Open connection __ seconds:
You can set how long the mail server should try to establish a connection to another host before it times out.

Read/write __ seconds:
You can set how long the mail server should wait for a response before it times out.

Custom Outgoing SMTP port

Port Number:
Enter a number if you don't want to use the default port number.

Related topic

Mail host settings