Generate a random email address.
The pentf configuration object. config.email needs to be set.
config.email
Text to put before the random characters. If no prefix is specified, the test name is used if available.
If config.email is 'foo@bar.com', something like foo+prefix129ad12@bar.com
'foo@bar.com'
foo+prefix129ad12@bar.com
Generate a random email address.