The homepage has a feature comparison with Sendgrid. Sendgrid doesn't have email receiving, inboxes, attachment parsing.

Yes it does. As far as I recall, all major email providers handle inbound email. Sendgrid, Postmark, Mailgun, SparkPost, AWS SES.

(I don’t think this compromises the value of AgentMail, just clarifying what is supported elsewhere.)

Yes, some providers support receiving via webhooks (or some other notification), but lack the inbox infrastructure that Gmail and AgentMail offer.

good point. i guess really the comparison is SES not gmail

Happy to add some color here. SES and other APIs lack inboxes, email threading, attachment parsing, semantic search, structured data extraction, and more.