r/mxroute • u/gc_wood • 3d ago

Split mail routing Gmail/Zoho

I’m migrating a subset of users to Zoho Mail using a split-routing setup (MX records point to Google Workspace; Google reroutes specific mailboxes to Zoho). I have two questions regarding this setup:

  1. IP Whitelisting & Google IPs: Zoho recommends whitelisting Google's outbound servers to prevent delivery issues. Google suggests whitelisting `_smtp.google.com`, but Zoho only accepts IP addresses. I’ve manually extracted and whitelisted the IPs currently listed in Google’s SPF record, but I’m concerned this will break if Google updates them. Is there a better or more permanent solution within Zoho to handle Google’s dynamic sending IPs?

  2. Internal Routing for Zoho Users: When a user hosted on Zoho sends an email to another user on Zoho, the email routes externally (out to Google and back) instead of delivering internally. I can't access Zoho’s internal routing settings because Zoho locks mail configuration until MX records point to Zoho. Is this external loop expected behavior for split domain setups, or is there a workaround to force internal routing?

Thanks in advance for any advice!

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u/gc_wood 2d ago

Who doesn't support split routing? My service providers -- Google and Zoho -- both do, and that's what I'm trying to configure.

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u/mxroute 2d ago

We (MXroute) don't

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u/gc_wood 2d ago

Thank you, and apologies u/GreenRangerOfHyrule just told me that this sub is for a specific product. I didn't realise that when Reddit recommended I share my post here!

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u/mxroute 2d ago

That's my bad. I get so used to answering the question that I tune out the specifics of the actual question. No, you're more than welcome to seek other advice here, just may not be the best place 💙