I have two domains. Say DominA.com and DomainB.com. All the mail for both domains is delivered to the same server. Every now and then if someone e-mails “To: someone@domainA.com, someone@domainB, someone@domainB.com” - the people in domainB.com don’t receive the e-mail, or vice-versa. Is this a Notes issue? Does anyone else have a similar problem? Although I am a Domino fan, I haven’t had this problem in the same situation but with Exchange.
You don’t say whether the sender is getting a delivery failure or the mail is ‘stuck’ in a mail.box somewhere. This information will help a lot in figuring out where the problem is.
If I understand your issue correctly, you have mentioned that you have two domains on the same server. In that case, connection documents are not required and the mails should get delivered by default.
Also, I feel the problem you are stating is a hypothetical situation, in which case, it would be greatly difficult for anyone to correctly respond to you.
I would suggest that you please send an email to the affected party and enable delivery receipts, etc. so that you can track where the mail is getting stuck.
Post back your response and someone may be able to help you.