SMTP Virtual Services and ESP
- Last Updated: March 20, 2026
- 1 minute read
- LoadMaster
- LoadMaster LTSF
- Documentation
If an SMTP Virtual Service (with 25 as the port) is created, the ESP feature is enabled for the Virtual Service when the Enable ESP checkbox is selected, but with a reduced set of options.
Enable ESP
Enable or disable the ESP feature set by selecting or deselecting the Enable ESP check box.
Connection Logging
Logging of connections can be enabled or disabled by selecting or deselecting the Connection Logging check box. The ESP logs can be viewed and downloaded by going to System Configuration > Logging Options > Extended Log Files.
Permitted Domains
All the permitted domains that are allowed to be received by this Virtual Service must be specified here. For example, if the Virtual Service should receive SMTP traffic to john@progress.com, then the progress.com domain must be specified in this field. When entering more than one domain, separate them with a space.
The use of Shell regular expressions is allowed within this text box.