AS11377 SENDGRID

SENDGRID is SendGrid, Inc. — now Twilio SendGrid — the transactional and marketing email delivery platform. This AS is one of the larger outbound-mail networks on the internet: it exists to originate email on behalf of tens of thousands of customer applications.

What it's used for

RIS sees 130 IPv4 prefixes carrying 263,680 addresses, no IPv6, and 22 observed BGP neighbours. That combination is diagnostic. A quarter of a million addresses behind only twenty-odd peers is not a transit carrier (which would peer with hundreds to thousands) and not an eyeball network; it is a platform that needs address space rather than reach. Email deliverability is scored per sending IP, so an ESP buys and announces large aggregates — 168.245.0.0/18, 159.183.64.0/18, 167.89.0.0/18, several /19s of 149.72.0.0/16 — purely to hand dedicated sending addresses to customers and to keep reputations isolated from one another.

Notable

The reverse DNS shows exactly that model at work. Shared sending addresses resolve to *.outbound-mail.sendgrid.net, while dedicated-IP customers wear their own names on SendGrid space — the sample includes o58.imod2.syr.edu, o2.mails.veracash.com, o1.sgmta.cw.com.tw and o5217.e.ops.jora.com. Customer-branded PTRs on the provider's own prefixes are a deliberate deliverability feature, not a sign the space has been leased away.

Interesting

The prefix registrants split between org SendGrid, Inc. and org Twilio SendGrid (TWILI-11) — a visible fossil of the 2019 Twilio acquisition, and precisely the intra-group registrant pattern that should not be mistaken for third-party address brokerage.