This'll click all the Show Email buttons and scrape the emails. There's a 750 ms (0.75 sec) delay between each click so it'll take about 15 sec to complete for the example search. I used Page load delay (ms): 6000.

yellowpages-south-africa.json

{
	"_id": "yellowpages-co-za",
	"startUrl": ["https://www.yellowpages.co.za/search?what=accounting+services&where=pinetown"],
	"selectors": [{
		"id": "listing wrappers",
		"type": "SelectorElement",
		"parentSelectors": ["_root"],
		"selector": "div.yp-object-result-item",
		"multiple": true,
		"delay": 0
	}, {
		"id": "Click Show Email",
		"type": "SelectorElementClick",
		"parentSelectors": ["listing wrappers"],
		"selector": "div.pb-1",
		"multiple": false,
		"delay": "750",
		"clickElementSelector": "b.idShowEmail",
		"clickType": "clickOnce",
		"discardInitialElements": "do-not-discard",
		"clickElementUniquenessType": "uniqueText"
	}, {
		"id": "Company name",
		"type": "SelectorText",
		"parentSelectors": ["listing wrappers"],
		"selector": "h5",
		"multiple": false,
		"regex": "",
		"delay": 0
	}, {
		"id": "Email",
		"type": "SelectorText",
		"parentSelectors": ["Click Show Email"],
		"selector": "div .fullDetailId a[onclick*=Email]",
		"multiple": false,
		"regex": "",
		"delay": 0
	}]
}