I've got a situation that seems to have stumped Verizon 2nd level techs.
I have a client who regularly sends email from his on-site server through a failover device (a CradlePoint switches back and forth between two ISPs in the event of one failing). One side sends email fine, the other side is a Verizon cellular modem. During the time when failover is switched to Verizon and only during this time, sent emails are bounced back as spam (550 NDR) from 99.9% of all recipients.
I believe the PTR record needs to be changed at Verizon to associate outgoing email with client's email domain. Verizon is having trouble making this change.
I have already fixed up DNS on the client side to have dual static IPs (see my last posted question).
Does anyone know how to reliably send email via Verizon Wireless?