This function seems to have a bug, when the quoted-printable string contains a "=" without the HEX code of a Character.
I use the regular quoted_printable_decode instead.(PHP 4, PHP 5, PHP 7, PHP 8)
imap_qprint — Convierte una string con comillas en una string de 8 bits
   Convierte la string con comillas string
   en una string de 8 bits (según la » RFC2045,
   sección 6.7).
  
stringUna string con comillas
This function seems to have a bug, when the quoted-printable string contains a "=" without the HEX code of a Character.
I use the regular quoted_printable_decode instead.