[R-pkg-devel] status of "possibly invalid URL/403 error" NOTEs?

[Ben Bolker]

   I have a package whose documentation includes the reference 
\doi{10.1137/18M1186411} which redirects here:
https://epubs.siam.org/doi/10.1137/18M1186411

Running R CMD check --as-cran on the package gives

Found the following (possibly) invalid URLs:
   URL: https://epubs.siam.org/doi/10.1137/18M1186411
     From: man/llig.Rd
     Status: 403
     Message: Forbidden

   I can access this perfectly well in the browser.

   Is there any way to avoid this (other than, say, including the URL in 
a form that does *not* provide a link so that R CMD check won't try to 
access it? (As Uwe Ligges says 
[here](https://stat.ethz.ch/pipermail/r-package-devel/2020q1/005195.html) 
(for a more obviously problematic case), "mention the URL in plain text 
but not link"

   Here Hadley Wickham says that these NOTEs can be ignored

https://twitter.com/hadleywickham/status/1358170607314235392

but "Hadley said it on twitter" is not an ideal source. The CRAN 
repository policy says that packages must pass checks without 
"significant" notes, but it's always hard to know what's significant and 
what's not ...

   There's a thread here: 
https://stat.ethz.ch/pipermail/r-package-devel/2020q1/005171.html

    Tangentially: is there a more convenient way to search the 
r-package-devel archives than googling (e.g.) 
"site:https://stat.ethz.ch/pipermail/r-package-devel  403" ?