Hi,

My company uses SendGrid to send out text messages to our clients, but recently we seem to have been blocked by AT&T. After sending each email text to our clients, SendGrid is receiving a 250 response from AT&T server, signifying the reception of the message. However, none of our clients are receiving those texts for the past couple of weeks. I'm just wondering what's going? Are our emails being received by ATT, but not routed to our clients? Are we blacklisted somehow? If so, how do we get whitelisted? Also, we've recently set up SPF on our server to allow SendGrid to send emails on our server's behalf during the reverse DNS lookup, but it does not seem to be working (We've experienced similar blockage from other carriers and SPF seems to have resolved the issue, but not working for ATT). This may be because our host has been blacklisted already and that blacklist needs to be lifted?

Please advice on this.

Thanks!