Support more than one label on SPF_BUILDER

[virtualroot]

This might be very handy

    SPF_BUILDER({
      labels: ['dev', 'production', 'staging'],
        parts: [
            'v=spf1',
            'include:mailgun.org',
            'include:spf.mailjet.com',
            '-all'
        ]
    }),

[tlimoncelli]

How would this work? Would they all point to the same "overflow" records?

[virtualroot]

I thought a simple iteration over label would be enough, but I found out that overflow, if defined, only works for @ label.

I think after the first SPF record all of them should include the same "overflow" records.

[tlimoncelli]

CC: @captncraig

[tlimoncelli]

This is stale. I'm closing this. Please re-open if needed. Thanks!