swiftmailer - failures by reference?

Question

I am using swiftmailer

Currently to record failures I use

if(!$mailer->send()) //failed

but,

I am aware that you can do

Pass a by-reference variable name to the send() or batchSend() methods of the Mailer class. If the Transport rejects any of the recipients, the culprit addresses will be added to the >array provided by-reference.

My question is,

Does if(!$mailer->send()) catch bounces? i send my emails one at a time as they all have modified contents, so I am never sending to more that one address at a time.

are there any benefits to me specifically by using the second method?