As I understand you want to define a custom sync rule that will filter based on domain suffix set in proxy address attribute with smtp.
You can create rule based on below screenshot.
In the above rule there are groups and clauses. Groups are separated by logical "OR" and clauses are separated by logical "AND".
I have created a rule with smtp and domain.com with clause and I have added another group with domain.com.
This means any proxyaddresses with smtp and domain.com will get filtered. Or any Proxyaddresses with domain.com will get filtered.
Try this and let me know if this works. Else we can set up a call to troubleshoot this further.
Please send us an email on azcommunity [at] microsoft [dot] com with Sub - Attn: Sandeg and following details in the email body:
Link to this thread/post
We can connect offline and discuss further on this.
Let me know if you have any further questions.
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