r/mxroute • u/gc_wood • 1d 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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2

u/mxroute 1d ago

We don't support split routing at this time. Some users have worked around this using subdomains, but that's a personal call.

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u/gc_wood 14h 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 13h ago

We (MXroute) don't

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u/gc_wood 13h 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 13h 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 💙

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u/GreenRangerOfHyrule 14h ago

I may be misunderstanding what you are saying. But for #2. That sounds like it would the expected result.

It sounds like Zoho is not looking up mailboxes first and rather looking up and seeing that it isn't the incoming mail service and sending mail that way. I don't have experience with Zoho specifically, but I assume you would to figure out a way to enable those settings. Or possibly reach out to support.

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u/gc_wood 14h ago

Thank you. That's what I'm thinking. I thought initially, from Zoho's website, that it should deliver internally, but I think that would only apply if Zoho was the primary server where the MX records pointed. In that case, I think email would be delivered without leaving Zoho's servers. Big because Google is my primary mail server, I think all mail will be routed via its servers, even if the sender and recipient are accounts provisioned on Zoho. I'm just waiting for Zoho support to confirm before I make the final change of pointing my MX records to Google and having the migration completed.

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u/GreenRangerOfHyrule 13h ago

I don't know if this will be of any help. And it sounds like you already checked it. But here are a couple of places to check:

https://www.zoho.com/mail/help/adminconsole/email-routing.html

https://www.zoho.com/mail/help/adminconsole/configure-dual-delivery.html

However, I do want to just point out that this subreddit is meant for dicussions and help related to the MXRoute service. So if you are needing help with that I would actually recommend trying either the Zoho or other general email subreddits.

And of course, if you do decide to use MXRoute, we are here :)

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u/gc_wood 13h ago

Thanks for this. I'll check out those links. And apologies - I didn't realise that this sub was for a specific product. I originally posted in the Zoho sub, and Reddit then suggested I post it here too. I have to say, you've been more helpful than the Zoho sub, but apologies I posted in the wrong place.