error in displaying pdf

[Globe Trotter]

Hi,

I have a strange issue in that my pdf attachments (or at least some of them) are getting their names converted to something like: '=?utf-8?Q?efficient=5Fkkmeans.pdf?=' in mutt. 

I don't think that this happened before. As a result, this is not being identified as a pdf and my mailcap file is unable to open it. 

Here is my mailcap entry:

application/x-pdf;                 mutt_bgrun "${PDFVIEWER:-zathura}" %s; test=test -n "$DISPLAY"; nametemplate=%s.pdf; description="PDF Document"
application/x-pdf;                 pdftotext -htmlmeta %s - | w3m -dump -T text/html; nametemplate=%s.pdf; copiousoutput

I am not sure if there are other file types which also have this issue but I was wondering how to I get around this? It may well be a consequence of the mailer that my correspondents are using but it certainly gets identified correctly in other (perhaps less exact) mailers.

TIA!