if you make a phpinfo() file in your roundcube directory do you see dom listed? something like this....
dom
DOM/XML enabled
DOM/XML API Version 20031129
libxml Version 2.6.32
HTML Support enabled
XPath Support enabled
XPointer Support enabled
Schema Support enabled
RelaxNG Support enabled
I've exact the same error (gentoo):
my phpinfo output says:
DOM/XML enabled
DOM/XML API Version 20031129
libxml Version 2.7.3
HTML Support enabled
XPath Support enabled
XPointer Support enabled
Schema Support enabled
RelaxNG Support enabled
and using:
dev-lang/php-5.2.8-r2 USE="apache2 berkdb bzip2 cli crypt ctype curl gd gdbm iconv imap mysql ncurses nls pcre readline reflection session spl ssl unicode xml zlib -adabas -bcmath -birdstep -calendar -cdb -cgi -cjk -concurrentmodphp -curlwrappers -db2 -dbase -dbmaker -debug -discard-path -doc -empress -empress-bcs -esoob -exif -fastbuild -fdftk -filter -firebird -flatfile -force-cgi-redirect -frontbase -ftp -gd-external -gmp -hash -inifile -interbase -iodbc -ipv6 (-java-external) -json -kerberos -kolab -ldap -ldap-sasl -libedit -mcve -mhash -msql -mssql -mysqli -oci8 -oci8-instant-client -odbc -pcntl -pdo -pic -posix -postgres -qdbm -recode -sapdb -sharedext -sharedmem -simplexml -snmp -soap -sockets -solid -spell -sqlite -suhosin -sybase -sybase-ct -sysvipc -threads -tidy -tokenizer -truetype -wddx -xmlreader -xmlrpc -xmlwriter -xpm -xsl -yaz -zip -zip-external" 0 kB
... apache restarted after recompiling php with xml enabled...
.. and the mentioned "Failed opening 'DOMDocument.php' for inclusion " above is also coming on my box. slocate fails to find a DOMDocument.php on my server... so missing
SOLUTION for ME:recompiled php once more
restared apache again
and errors were gone, ascii + html mails are now displayed and logfile is empty.
regards,
Georg