Send Email steps error with 'The specified string is not in the form required for an e-mail address'

Issue

All Workflows with a Send Email step are going into error state, with the following message:

Resolution

Verify that the FROM ADDRESS Environment Library field in K2 Management's Environment Library is set to the correct address.

Related Links

https://help.nintex.com/en-US/k2five/userguide/5.4/default.htm#K2-Management-Site/Environment-Library/Environment_Library.htm?TocPath=Administer%257CK2%2520Management%257CEnvironment%2520Library%257C_____0