I need to go confirm the config steps for DNS... for exchange.
exchange2010 part of one domain trust and forest, set to also accept mail from other domain.
1. Exchange server pub IP188.8.131.52
primarydomain.com hosting company cpanl DNS manager A record 184.108.40.206 for mail.primarydomain.com.
svracceptdomaintoo.com same hosting company diff cpanl DNS manager A record 220.127.116.11
1a. Our internal DNS svr for primarydomain.com has A record for 18.104.22.168
2. MX records for both(via same hosting co but separate/their own cpanl access) set to point to External filtering company that has our public 22.214.171.124 for mail.primarydomain.com and MX records to use. Priority 10 and 20.
3. SPF under cpanl of @primarydomain.com DNS mgr is setup like "v=spf1 +a +mx include:primarydomain.com ip4:126.96.36.199 ptr:primarydomain.com -all"
Exchange 2010 SMTP connector FQN matches A record - mail.primarydomain.com
Not sure if something is missing, all is right if reverse DNS entry(ptr record) needed somewhere?