Zoho CRM SMTP Setup at Volume - Email Relay

Zoho CRM caps mass email at 250 a day on Standard, 500 on Professional, 1000 on Enterprise and 2000 on Ultimate, and that number is per organisation per day, not per user. Individual emails run on a separate allowance of 300 per confirmed user per day on paid editions. Everything leaves through Zoho's shared servers unless you configure Email Relay, which points CRM at your own SMTP host on port 25, 465 or 587 and lets you run up to five relay servers per domain.

That relay setting is the whole article: the difference between renting Zoho's IP reputation and owning yours.

What the limits actually are

Source: Zoho CRM's email limits page. Zoho revises these, so check the current page before you build a plan around a number.

The mass email figure is the one that bites. It is per organisation, so extra user seats do nothing for it, and the count includes autoresponders, schedulers and macros alongside campaigns. An Enterprise account running three autoresponder sequences can burn most of its 1,000 before anyone presses send. A day runs midnight to 11:59pm in your org's time zone.

Individual email works the opposite way. It scales with confirmed users at 300 each, so a 20-seat Enterprise org gets 6,000 individual emails a day but still only 1,000 mass.

Where the limit actually stops you

CRM-triggered operational mail fits comfortably. Full-list marketing does not. Anything above roughly 1,000 recipients in one send is where people go looking for the relay setting, and it is the same wall HubSpot users hit from the other direction, where the constraint is the marketing contact bill rather than a daily cap.

What Email Relay does

Email Relay hands your outbound CRM mail to an SMTP server you control instead of Zoho's. Per Zoho's relay documentation:

Per-email-type routing. Each relay carries workflow, mass or individual mail. Split them and a bad campaign cannot damage the IP delivering your quotes and deal notifications. Zoho's own servers have no such separation.

Five servers per domain. Enough for separate IPs per stream with a spare, or a split by business unit if one CRM runs several brands.

Automatic fallback. If your relay fails, Zoho sends from its own servers. Nothing is lost, but the message loses your IP and your authentication alignment, so it can land differently. Monitor for it rather than assuming fallback is free.

Setting the relay up

Fifteen minutes once the server exists. In CRM: Setup, Channels, Email, Email Deliverability, Email Relay, then + New Server.

Port choice is not a preference. Port 25 is blocked outbound by most cloud hosts, so it only works where the provider permits it. Port 587 with TLS is the submission port and the right default, and 465 is implicit TLS if your server prefers it. Breakdown in SMTP ports 25 vs 465 vs 587 vs 2525.

Before you save, test the credentials from a shell, so an auth failure shows as a clear error rather than silent fallback to Zoho:

openssl s_client -starttls smtp -crlf -connect mail.yourdomain.com:587

Then send one CRM email of each routed type and check the Received: headers name your server. If they name a Zoho host, the relay is not being used.

Which mail goes where

The last row is the one people resist and then agree with. Zoho CRM's mass email is built for CRM segments, not a 50,000-address list, and the daily cap says as much. If the newsletter is your real volume, run it from self-hosted campaign software pointed at the same server and let CRM carry only CRM mail. See SMTP for CRM and marketing automation.

Individual sales mail is the one stream worth leaving on Zoho. Volumes are small and the per-user 300 allowance is rarely the constraint.

The deliverability change, and why it cuts both ways

Moving off Zoho's servers changes who owns your reputation. That is an improvement only if you do the authentication work.

On Zoho's shared infrastructure your mail leaves from IP ranges used by thousands of other customers, and you get no visibility into their behaviour. On your own IPs nobody else can burn your reputation. Nobody else can carry you, either.

The alignment gain is the concrete part. Once the mail leaves your server:

• SPF must list your relay's IP in your domain's TXT record.
• DKIM must sign with a key published under your domain, not Zoho's.
• DMARC then has something to align against, because the From domain, the SPF domain and the DKIM domain finally match.

That alignment is what Gmail's bulk sender rules require. Google mandates SPF, DKIM and DMARC for anyone sending more than 5,000 messages a day to Gmail addresses, and holds spam complaints under 0.30% with a target of 0.10% (Google's sender guidelines). Full record syntax is in our SPF, DKIM and DMARC setup guide.

Skip this and the relay makes delivery worse, not better. You will have swapped a warm shared pool for a cold IP with no authentication.

Warm-up, because the IPs are new

A new relay IP has no sending history. Zoho's did. Ramp or spend a week in deferrals.

Watch 4xx deferral rates, not open rates. A rising 4xx from Gmail or Microsoft means hold the current volume two more days. Four to eight weeks to full volume is normal even if you have sent through Zoho for years, because receivers score the IP as well as the domain. Detail in the IP warm-up schedule.

The CRM case has one advantage: workflow mail is exactly the traffic you want during warm-up, since it goes to people who just did something in your product. Route that stream first, then add mass email once the IP has three clean weeks.

Limits and costs compared

The relay row changes the shape of the bill. A CRM seat does not scale with email volume and a one-time build does not renew, so the marginal cost of the 100,000th email is near zero. Contact-tier pricing does the opposite: an unengaged 30% of your list costs the same as your buyers every month, mailed or not. Worked through in Zoho Campaigns vs a dedicated SMTP server.

Campaigns is not a bad product. It has the builder, journeys and signup forms a relay does not. The point is you can keep the suite and stop renting the sending.

Setup checklist

Work in this order.

1. Confirm your current edition's mass email cap on Zoho's limits page.
2. Count what you actually send per day, split by workflow, mass and individual.
3. Provision the SMTP server and its IPs, with PTR records matching the HELO hostname.
4. Publish SPF authorising the relay IPs, and DKIM under your sending domain.
5. Set DMARC to p=none and read reports for two weeks before enforcing.
6. Add relay server 1 in CRM for workflow mail, port 587, TLS, auth on.
7. Send one test workflow email and check the Received: headers name your host.
8. Warm the IP with workflow traffic for two to three weeks.
9. Add relay server 2 for mass email once the first IP is clean.
10. Set a daily mail limit on each relay slightly below your server's real capacity.
11. Watch for fallback: mail arriving from Zoho hosts means your relay failed.
12. Move the full-list newsletter to MailWizz or Mautic on the same server.

Step 11 is the one people skip. The fallback is a good safety net and a terrible blind spot: a broken relay looks like working email until someone checks headers.

How BulkEmailSetup helps

We build the SMTP server your Zoho CRM relay points at: your own host and IPs, PTR, SPF, DKIM and DMARC on your sending domain, MTA tuning, bounce handling and a warm-up plan. You keep every CRM record, workflow and deal-stage trigger. What changes is the IP the mail leaves from, the reputation attached to it, and the daily ceiling.

Basic is $549 one-time, covering 1 SMTP server, 3 dedicated IPs, 25,000 emails/day and unlimited contacts. Higher tiers scale to 15 IPs and 200,000 emails/day. See pricing, or read SMTP for CRM and marketing automation for how the CRM and newsletter layers fit on one server.

Frequently asked questions