Hi all,
Just to tell you that it is possible to send mass emails by merging the content of your NextCloud address book on the Writer document of your choice in LibreOffice / OpenOffice.
This is possible by installing the following extensions:
OAuth2OOo
jdbcDriverOOo
vCardOOo
smtpMailerOOo
After installing these extensions you would be able to send LibreOffice Writer documents by email, merged into your NexCloud address book, in HTML format with possibly attached files which can if necessary be merged and converted to PDF format.
Good use and thank you for reporting any malfunction.