I found this bug report in my open tabs in firefox and I forgot why I opened it in the first place. Anyway, I took a quick look and found that it's been deprecated upstream:
https://metacpan.org/pod/Mail::Sender "Mail::Sender is deprecated. Email::Sender is the go-to choice when you need to send Email from Perl. Go there, be happy!" Since it has no reverse dependencies and last upload was in 2010, (it never made it into stretch) I guess it should be pretty safe to remove it. Cheers, Alex
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