Mail Connectors → Mail Senders → SMTP Direct Sender → Settings tab

The SMTP Direct Settings tab lets you set how VPOP3 will send mail using SMTP Direct

This setting tells VPOP3 the IP addresses of the DNS servers it should use to find the recipients' mail servers. Separate multiple addresses with commas.

If you leave this blank, then VPOP3 will use the DNS servers set in the Misc Settings.

Ideally, VPOP3 should be using local caching DNS servers. DNS servers in some routers are not very good, so if you have a local DNS server, we recommend you use that. Windows Server editions come with a DNS server, another good DNS server for Windows is SimpleDNS. Bind for Windows is also good, but is more complex to configure. Alternatively, for light usage, you could use Google's DNS public servers on 8.8.8.8 and 8.8.4.4.

DNS overrides let you 'fake' DNS entries for certain domains. For instance, if you want most of your mail to be sent using MX direct, but mail to *@gmail.com to go through your Internet provider's SMTP relay server, you could add an entry like

gmail.com    smtp.myisp.com

This will make VPOP3 find 'smtp.myisp.com' when it looks for the MX servers for 'gmail.com'

If your ISP requires SMTP authentication, or a different port number you can specify these as well

This option tells VPOP3 how many recent DNS results it should cache internally. VPOP3 will remember up to this many recent DNS results, but it will also honour the DNS result 'Time to live' (TTL) setting, so entries may be removed from the cache even when the cache isn't full.

If the DNS Servers which VPOP3 is using are local DNS servers with their own caches, then you should usually set VPOP3's own DNS cache size to a small number.

This value tells VPOP3 how many messages it should send at once. 10 is a good starting number. If you set it too high, then throughput will be limited because of the large number of simultaneous connections. If you set it too low, then there will be wasted time as VPOP3 is doing DNS lookups and connecting to remote servers and is not sending messages.