Pedro David Marco wrote:
Is there any way to know whether a Sendgrid IP is shared or dedicated?
Use the FCrDNS data and one or another of the X-Spam-Relays metaheaders. It should be possible to quickly refine these to "good enough", if they're not already (watch for word wrap):
header SENDGRID_SHARED_1 X-Spam-Relays-Untrusted =~ /^\[[^\]]+ rdns=[\w\d.]+\.shared\.sendgrid\.net /
header SENDGRID_SHARED_2 X-Spam-Relays-Untrusted =~ /^\[[^\]]+ rdns=[\w\d.]+.outbound-mail.sendgrid.net /
I suspect the second matches a somewhat different slice of their services than you're asking about, but I can't say I can really tell the difference from the outside.
-kgd
