sudo apt-get update # Fetches the list of available updatessudo apt-get upgrade # Strictly upgrades the current packagessudo apt-get dist-upgrade # Installs updates (new ones) https://askubuntu.com/questions/733434/one-single-command-to-update-everything-in-ubuntu/733439 You need to take a step back and figure out what you're doing. If you're going through the trouble of setting up DMARC I'd also set up DKIM. All 3 (SPF,DKIM and DMARC) rely on DNS records, so if you don't have a local DNS then you aren't going to be able to do much. You can setup a local NS through Vesta: https://vestacp.com/docs/#how-to-setup-vanity-nameservers You will then need to go to your domain registrar and point it at your domain name servers where you can then set all your own SPF, DKIM and DMARC records. Or You can use your registrars name servers if they let you specify your own TXT entries and do it all there. The entry would look something like this, I just generated it using a free DMARC generator:
Type: TXT
Host/Name: _DMARC.stockdiv.com
Value: v=DMARC1; p=quarantine; rua=mailto:postmaster@stockdiv.com; ruf=mailto:postmaster@stockdiv.com; sp=quarantine; fo=1; adkim=s; aspf=s
OR Ask nicely for the required entries to be made on the Helio nameservers (SPF seems to already be done this way) OR Use cloudflare as a nameserver, if your registrar doesn't allow TXT entries.