Paul S. We deal with this exact pattern a lot. Apollo (and most contact enrichment tools) will happily push a record into Salesforce even if the email is dead, the phone format is wrong for the country, or a near-duplicate already exists under a slightly different name or company. The sync itself works fine, the problem is what it's syncing.
What's helped teams we've worked with: validate and dedup before the record ever writes to Salesforce, not after. Catch invalid emails, bad phone formats, and fuzzy duplicate matches (not just exact matches) at the point of entry, so Apollo, LeadIQ or Clay are only ever pushing clean records into SFDC in the first place.
Happy to hop on a quick call if useful, we do this specifically for Salesforce and Dynamics environments.
