The links are to the appendix within the same document and they all work fine on my pc in odt format using Libre, but when I try to send them via outlook the receiver is unable to open links.
And why do you assume this being a problem of LibreOffice, if the receiver ist not able to (correctly) open your .odt file? If you don’t provide any information, how the receiver opens the file (does he/she use LibreOffice or does he/she open the files using some other application like MS Word) nobody will be able to provide a sound answer without speculating / assuming too much.