Im trying to setup email alerts for WAN disconnect/connect when a router fails over to the LTE connection (2862Ln). The problem is the emails are not sending and all i get is the following error:

Warning! Email SMTP server could not get ip!.
Email send Failed

I have set the router DNS to the same as LAN1 which is OpenDNS and GoogleDNS and also tried hard coding the SMTP Server IP but the same issue. I think the issue is that when WAN1 goes down there is no internet to send the email and when the LTE connects the send email is to quick and the LTE hasn't fully finished connecting. Anyone else have any experience of this?

We are trying to send emails to an Office365 account.