Ask HN: What service does Robinhood use for emails

I always get trade confirmation emails instantly whereas many apps take a few seconds / a minute to deliver forgot password, authentication code, etc. emails. Would love to be able to incorporate whatever service Robinhood uses into apps I build.

Looking at a recent email I received from them, it appears to originate from o26.email.robinhood.com, which resolves to 149.72.71.69, which in turn (per ARIN) belongs to Sendgrid. Other emails I've received vary in the first portion of the 'received from' value (e.g. o2, o6, etc.) YMMV.