Extracting emails from strings

[jvwong]

In some cases, there are multiple emails separated by spaces in an author email reference.

E.g. PMC10632954

...
<author-notes>
	<corresp id="c1-ETM-26-6-12261">
		<italic>Correspondence to:</italic> Professor Zhiming Zheng, Department of Neurosurgery, Shandong Provincial Hospital Affiliated to Shandong First Medical University, 324 Jingwu Road, Jinan, Shandong 250021, P.R. China 
		<email>doctor_pan0529@126.com zhiming0119@126.com </email>
	</corresp>
...