MailerZ vs ImprovMX: Which Custom Domain Forwarder Fits You?

Quick answer for mailerz vs improvmx

If you want Gmail as the store, exclusive MX, envelope SRS, and Header From left alone, either product can be a hop. MailerZ is the control plane we operate: HOLD on Free, leftover MX as a hard stop, stored hops, Solo at $40 per year when send-as starts. ImprovMX is the closest competitor class—see ImprovMX — product documentation and their pricing page. Product path: MailerZ pricing, features, migrate from ImprovMX. MX physics is in IETF RFC 5321 — Simple Mail Transfer Protocol.

Do not invent SOC 2, ISO, HIPAA, or an inbox SLA for MailerZ. ImprovMX publishes a 99% uptime guarantee on Free and paid cards as of that quote date. We do not match that sentence. We also do not claim we “win deliverability.” Inbox placement stays with Gmail and Outlook.

Google’s helpful-content guidance is about pages; see helpful content. A comparison that copies last year’s prices without a live check is a different kind of leftover.

The user problem and the decision criteria

Teams pick a forwarder because Workspace seats feel expensive for hello@ and billing@. The decision is which hop they will staff, not which logo sounds more “enterprise.” MailerZ vs ImprovMX fails when someone publishes both MX sets to “try both” or when they pick on alias count alone and ignore unknown policy.

Technical mail flow

Either product becomes the MX owner. Senders resolve MX, offer the envelope, and stop after a 250. The hop then forwards to Gmail or Outlook. MailerZ rewrites only the envelope with SRS. Header From stays the original sender. If ImprovMX documents a different rewrite, quote their docs—do not assume they match. Two MX products mean some senders never reach the hop you are watching.

Self-send from Gmail to Gmail can skip public MX. Foreign probes are the gate on either vendor. Leftover Google or Microsoft MX next to a forwarder is the same incident whether the forwarder is MailerZ or ImprovMX.

Daily forwarding caps are a product difference. ImprovMX states they pause forwarding when you hit the daily limit until rollover or upgrade—quoted from that pricing FAQ. MailerZ publishes monthly outgoing and store windows on pricing. Do not treat either pause as “delivered.” Empty history plus a cap is a policy stop, not leftover MX—unless leftovers also exist.

Step-by-step setup and decision path

1. Write the job in one line

   Inbound only, or inbound plus send-as. HOLD unknowns, or you will name every alias. One domain, or a fleet.

2. Quote both pricing pages the same day

   MailerZ on /pricing. ImprovMX on their pricing URL. Screenshot the cards. Prices move.

3. Build the map on the winner before you cut

   Aliases and destinations live while old MX stays exclusive. Config parallel is safe. Dual MX is not.

4. Publish one exclusive MX set

   Delete the other forwarder, Google, Microsoft, registrar, and parking hosts the same hour.

5. Foreign probe

   Unique subject. History or log. Header From intact. Destination search. Then send-as if paid.

6. Drain the loser without its MX

   Keep the old dashboard if you need logs. Do not leave its MX published “until we are sure.”

Failure modes and proof

Proof is a job line, two live quotes, one MX listing, and a foreign-probe row. Agencies run this per zone. Client A can be MailerZ while Client B stays on ImprovMX. Mixing both MX on one zone is leftover MX with a comparison spreadsheet.

MailerZ workflow and product boundary

MailerZ is inbound MX plus authenticated SMTP. Envelope SRS only. Header From never rewritten. It is not IMAP, not Workspace, not an open relay. Unhosted SMTP is 550 / 550 5.7.1.

HOLD stores unknown local-parts on Free. Free is one domain, three aliases, 14-day store, send-as disabled, SMTP and API disabled. Solo is $40 per year: 3 domains, 15 aliases, 90-day store, 1,000 outgoing, five outgoing per hour, unknowns forwarded. Starter is $8 or $80. Business is $19 or $190. Agency is $39 or $390. Confirm pricing. Limits are not an inbox SLA. No SOC 2 claim lives here.

Features describe routing. They do not make ImprovMX a worse hop by slogan. Paid plans do not buy a bake-off. They buy send-as and higher caps on this product.

Cost, alternatives, and live quotes

ImprovMX on 9 September 2026 listed Free at $0 (1 domain, 25 aliases, 500 forwarded per day, 7-day log, 99% uptime line, no SMTP send on that card). Premium $9 per month (30 domains, 100 aliases per domain, 5,000 forwarded per day, 6,000 SMTP per month, logs up to 180 days). Pro $24 per month (100 domains, 200 aliases per domain, 15,000 forwarded per day, 30,000 SMTP per month). Light $50 per year (5 domains, 25 aliases per domain, 5,000 forwarded per day, 25 SMTP per day). Enterprise custom. Re-open improvmx.com/pricing before you buy. Those numbers are a dated quote, not a contract we control.

Time is a line item. A dated quote costs less than a year on the wrong cap. Leftover MX costs more than either Free plan. A Free-plan send-as argument still costs more than the upgrade on the product you chose.

What Free actually includes

MailerZ Free is a receive path: one domain, three aliases, HOLD unknowns, 14-day store, send-as disabled, SMTP and API disabled. It is enough to prove exclusive MX and a foreign probe. It is not enough to print twenty role addresses or to send as the domain from Gmail.

ImprovMX Free, on the quoted card, is also inbound-first: one domain, 25 aliases, 500 forwards per day, 7-day log, API, standard support, and they print 99% uptime. They say Free stays. They also say Free has no SMTP send on that comparison table. If you need to send, you are comparing paid cards on both sides.

Twenty-five free aliases look like a win until catch-all or guessed names flood the destination. MailerZ HOLD is the conservative default. If you want that default more than the alias count, MailerZ Free fits. If you already have a named list of twenty strings and will not catch-all, their Free alias count may fit—quote them, then still delete leftover MX.

Seven-day versus 14-day store is recovery window, not holiness. MailerZ paid moves to 90 days. They list up to 180 days on paid cards. If counsel needs longer, export the destination Gmail. Neither log is a legal-hold product we will claim.

API access on their Free card is a real difference if you provision aliases from code. MailerZ is a dashboard-first hop in this article. Do not invent an API we did not publish. If you need their API, that is a job line, not a reason to dual-publish MX.

Send-as and SMTP caps

MailerZ Solo is $40 per year with published hourly and monthly send-as limits. Starter, Business, and Agency raise caps. Confirm pricing. Unhosted or unauthorized send is 550 5.7.1. Free has no send-as. Do not mix that 550 into an inbound leftover-MX ticket.

ImprovMX Premium listed 6,000 SMTP sends per month; Pro 30,000; Light 25 per day. Enterprise unlimited on that table. If your WordPress form or app will exceed Solo, quote both paid pages the same morning. Volume is a calculator, not a brand story.

Neither product is a campaign sender. CAN-SPAM still applies if you mail lists—see US Federal Trade Commission — CAN-SPAM compliance guide. Open relays are out of scope. Verified domain send is the point. SPF, DKIM, and DMARC must match the hop you send through. Two SPF records permerror. IETF RFC 7208 — Sender Policy Framework (SPF) and IETF RFC 6376 — DomainKeys Identified Mail (DKIM) do not care which forwarder logo is on the invoice.

Gmail send-as still needs their SMTP settings and a two-direction probe. Outlook the same. Composer UI is not proof. A unique subject to a third mailbox is proof.

HOLD versus more aliases

Attackers guess billing@, admin@, and founder names. A forwarder that delivers every guess trains Gmail. MailerZ HOLD keeps unknowns in the store for review. Paid FORWARD is a choice you write down. ImprovMX rules and catch-all behavior must be quoted from their docs the day you decide. Do not assume they HOLD.

If you pick ImprovMX for 25 aliases and then enable a wide catch-all, you bought alias count and spent it on guesses. If you pick MailerZ Free and then complain you cannot print twenty roles, you bought HOLD and three names. The mismatch is the job line, not the logo.

Agencies: do not copy Client A’s catch-all onto Client B because the comparison sheet said “ImprovMX has more aliases.” Per-zone unknown policy. Per-zone MX owner. Per-zone quote date.

Destination copies—two founders on one public string—are a map after one hop exists. They are not a reason to run MailerZ MX beside ImprovMX MX. Two stores, one owner.

Leaving ImprovMX without leftover MX

Screenshot their MX. Build MailerZ aliases. Cut exclusively. Delete ImprovMX hosts the same hour. Turn off anything in their panel that can republish DNS. Query two resolvers. Foreign probe. Drain their logs without their MX. Close when TTL plus a day is quiet.

The reverse is the same physics. If you leave MailerZ for ImprovMX, delete MailerZ names the same hour. We are not helped by leftover MailerZ MX on a domain we no longer operate. Offboard is exclusive too.

Registrar email and parking MX still appear during these cuts. Re-query after website saves. Night operators who add both forwarders “to test” recreate leftover MX with extra branding.

Rollback is one dated exclusive set. Restoring both ImprovMX and MailerZ is the split you already had. Wait TTL. Probe the owner you restored.

Legal hold is an export. It is not a second live exchanger. Two-factor on the destination stays required. Open a held body for break-glass and expect an audit row. That is a control, not SOC 2.

If a second operator needs the order without a call, send this page, leftover MX troubleshooting, and the migrate-from-ImprovMX path. Job line. Live quotes. Exclusive cut. Foreign probe. That order prevents a bake-off.

Paid plans do not change the physics. Solo, Starter, Business, Agency, Premium, Pro, Light—still one inbound owner. The upgrade changes caps. It does not merge two MX products.

IPv6 versus IPv4 on the new MX hostname is reachability after names are exclusive. Do not republish the old forwarder because AAAA failed. Fix the host. History will show whether the new hop accepted the envelope.

The artifacts that close mailerz vs improvmx are a job line, two dated pricing screenshots, one resolver listing, and a foreign-probe 250. Everything else is logo comfort. Logo comfort is how leftover MX survives a quarter.

Agencies and mixed fleets

A fleet can mix products per zone. Client A on MailerZ and Client B on ImprovMX is fine if each zone has one exclusive MX owner. A fleet that publishes both hops on one zone is leftover MX at scale. The comparison sheet is not a DNS record.

Standardize the job line in the intake form: alias count, unknown policy, send-as, API, yearly versus monthly. Then quote both pages. Then pick. Do not let a salesperson add ImprovMX MX “as backup” beside MailerZ. Backup MX to another product is a second owner.

Offboard must name the product you are leaving. Delete those hostnames. Filename the screenshot with the zone. If you copy last month’s MX set into the wrong client, you have theater plus leftover MX.

Quote Agency at $39 or $390 when the MailerZ fleet needs more domains. Confirm pricing. Their Enterprise is custom. Do not invent a partner discount we did not publish. Do not invent theirs.

Shared SMTP across clients is a later article. For this comparison, the agency risk is treating alias count as the only column and ignoring HOLD. Guessed names on a client domain become the agency’s spam problem in the destination Gmail you still staff.

Night operators who “just add the other MX to test” after a sales call recreate the split. Test with aliases live and old MX exclusive, then cut. Do not test with two forwarders published.

What we will not claim

We will not claim MailerZ has better inbox placement than ImprovMX. Placement is Gmail and Outlook. Header From preservation helps authentication survive a hop. It is not a guarantee the destination will love the sender.

We will not claim SOC 2, ISO 27001, or HIPAA. Controls live on security. We will not claim a 99% or 99.99% uptime number. They print 99% on those cards. Quote them. Do not copy the number onto MailerZ pages.

We will not claim their Free plan is worse because it is older. They have forwarded since 2013 on their FAQ. Longevity is a real trust signal. It is not leftover MX physics. Exclusive MX still wins.

We will not claim their refund policy or VAT handling. Their FAQ covers cancel, refund, and VAT. Quote that page if procurement asks. Our refund language lives on our legal pages. Do not mix the two in a sales script.

We will not claim MailerZ pauses the same way they pause at a daily cap. If you hit MailerZ limits, read pricing and history. If you hit theirs, read their limit FAQ. Empty history plus leftover MX is still leftover MX first.

We will not claim a customer quote. We will not invent review counts. Helpful content is a job line and a live quote, not a testimonial mill.

Two-factor on the destination remains required after either cut. HOLD review is still a weekly job if you store unknowns. Open a held body for break-glass and expect an audit row. IPv6 failures are host problems after exclusive names exist. Registrar saves republish. Re-query.

Send-as remains a second ticket. Free on both sides, as quoted, does not send. Mixing 550 5.7.1 into an inbound comparison is how the ticket never closes.

If you need IMAP folders on the domain, neither Free forwarder is the product. Quote Fastmail, Workspace, or another host live. That is a different class. This page stays in the forwarder class on purpose.

Regex and webhook rules are a real ImprovMX paid-card story if their current docs still list them. MailerZ maps named aliases and HOLD or FORWARD. If your intake form is “route mail matching a pattern to Slack,” quote their rules docs the same day. Do not invent MailerZ regex. Do not invent theirs after a redesign.

Seats on MailerZ are people who operate the map, not mailbox seats. Free is one seat. Do not sell Agency as Workspace. Do not sell their Enterprise as our Agency. Procurement that asks for a named account manager should read their Enterprise card and our /contact page. We will not invent a CSM.

Webhooks on their Premium card, if still listed when you quote, are not MailerZ hop history. History is SMTP evidence we show for hops we accepted. A webhook is their integration. Pick the evidence you will staff at 2 a.m.

How to run the bake-off without leftover MX

A bake-off is two sequential exclusive publishes, not two MX sets. Recreate routes on MailerZ, cut MX, probe, write results. Restore ImprovMX MX only if you rollback, then delete MailerZ MX. Calling dual MX an A/B test is how you A/B split mail.

Score objects, not vibes. Routing depth: do you run regex or webhooks today. Unknown policy: do you want HOLD visible. History: do you need destination SMTP stored. Seats: do humans share a dashboard. Volume: human replies versus campaign SMTP. Write yes or no. The product that matches the yes column wins.

Re-read ImprovMX pricing the morning you decide. Our alternative page quoted Free and Pro shapes that can move. MailerZ numbers in this article are the published ladder. Mixing a remembered ImprovMX number with today’s MailerZ page is how RFPs lie.

Seats are not aliases. MailerZ Starter is five seats and fifty aliases. ImprovMX counting may be aliases per domain. If three people must open history, seats matter. If one admin maps twenty names, aliases matter. Do not let “unlimited” language hide the object you are short on.

Send-as honesty: MailerZ Solo is 100 outgoing and 5 per hour. Business is 400 and 15. Agency is 800 and 25. If a stakeholder says “we send a lot,” ask for last month’s human From count. Campaign mail goes to a bulk sender on either choice.

Support expectations differ. A mature pure-forwarder may win on routing tickets. MailerZ wins when the ticket is HOLD versus destination 5xx. Pick the ticket type you actually file.

After you choose, the other product becomes a login keep. Delete its MX the hour you cut. Cancel after probes. The comparison article ends when leftover MX is gone, not when the blog tab closes.

If neither product fits because you need IMAP, stop comparing forwarders. Buy a store. This bake-off will not grow Calendar.

FAQ

Key takeaways

• MailerZ vs ImprovMX is same-class: forwarders into Gmail, not IMAP suites.
• Quote both pricing pages the day you decide. Cards move.
• MailerZ Free: 3 aliases, HOLD, 14-day store, no send-as.
• ImprovMX Free (2026-09-09): 25 aliases, 500/day, 7-day log, no SMTP on that card.
• We do not copy their 99% uptime sentence. We publish no inbox SLA.
• Dual MX is leftover MX. One owner. Foreign probe.
• Solo $40/yr starts MailerZ send-as. Their paid SMTP caps differ—quote live.
• Envelope SRS only. Not SOC 2. Confirm /pricing.

Conclusion and next action

If you want a forwarder, name the job and quote both pages. MailerZ fits HOLD, leftover-MX discipline, and a yearly Solo send-as start. ImprovMX may fit if their Free alias count or API is the job—quote them. Do not run both MX sets. Start free on one domain if that map is the one you will staff.

Review when either pricing page changes, and quarterly otherwise. Author: MailerZ editorial, Secuno LLC.