This happens regularly and makes SendGrid totally useless for transactional E-mail (I prefer to send it myself) and problematic for things like product updates.
I complained to them about this problem many times and it is my impression that this is a way to force-upsell customers to higher plans with dedicated IPs.
They usually act within 24h to enable sending if you have set up everything.
I'm just looking for something that doesn't cost an arm and a leg for the minimal email volume I send, and that has better deliverability than sending myself with a VPS, as there's usually at least one bad actor in any /24 your typical VPS will land in and that punishes your deilverability.
Moved to SES and been smooth sailing since (and a lot cheaper).
The service at a technical level is pretty good. It does the job, the pricing is fine, and deliverability is good. I think their IP address space is considered a bad neighborhood by some spam filtering systems though, since we can't send email to systems protected by Mimecast (sorry Red Hat, Packt, Siemens, et al.) despite our own dedicated IPs having very solid reputation and histories.
Opted just not to use Twilio.
It's bizarre because they own Authy so could have pushed more people towards that instead.
This being said, it feels unfair when you try to comply but somebody fucks you over.
