The patchwork of anti-phishing and anti-spamming measures like SPF and DKIM require DNS TXT records. Allowing mail from an IP address would likely be used almost exclusively for spamming.
Congratulations, you are one of the less than 1 out of 10.
AGM is great for stationary batteries, and has a place in vehicles but they will probably be replaced by lithium chemistry batteries in the coming decades as well as cost is coming down further.