Email routing capacity planning is counting domains, named aliases, operator seats, monthly outgoing mail, hourly send-as, and store days against a live plan card before you print hello@ on ten sites. It is not guessing “Agency sounds big.” It is not treating a cap as an inbox-placement SLA. HOLD review is staff time. Free is one domain and ten aliases. A noun list times a fleet will not fit Free.
Quick answer for email routing capacity planning
Spreadsheet zones × nouns, plus extras, plus send-as volume if that is in scope. Pick the card that fits with headroom. Product path: features, pricing, migration planner, delivery recovery. MX is still IETF RFC 5321 — Simple Mail Transfer Protocol. Quote ImprovMX pricing if you compare hops—do not copy their numbers onto ours.
Free: 1 domain, 10 aliases, 1 seat, 14-day store, send-as disabled, SMTP and API disabled. Solo $40/yr: 5 domains, 25 aliases, 90-day store, 2,500 outgoing, 20/hr, unknown forwarded. Starter $8/$80: 8 domains, 50 aliases, 5 seats, 5,000 outgoing, 40/hr. Business $19/$190: 25 / 200 / 25, 12,000 outgoing, 60/hr. Agency $39/$390: 100 / 500 / 50, 20,000 outgoing, 60/hr. Confirm live cards. No SOC 2. No inbox SLA.
Helpful capacity pages show the math: people-first content.
The user problem and the decision criteria
Sales promises “we’ll add careers, press, and send-as for the form” on Free. Launch day the fourth alias does not exist and the form 550s. The useful plan is a count with a named card. The useless plan is “we’ll upgrade if we hit it.”
| Question | If yes | If no |
|---|---|---|
| Zones × nouns ≤ alias cap? | You can print the list. | Collapse extras or change cards. |
| Send-as in scope? | Paid plan. Count hourly too. | Inbound-only. Free may fit one zone. |
| HOLD default? | Budget review time. | FORWARD is a paid choice per zone. |
| Ten clients on Friday? | That is a cut plan, not capacity. | Still count before intake. |
| Treating 20,000 outgoing as a campaign? | Wrong product class. | Good. Operational mail only. |
Technical mail flow
Capacity does not merge zones. Each zone still has one inbound owner. IETF RFC 5321 — Simple Mail Transfer Protocol picks MX for one name. A fleet on Agency is still N exclusive MX sets. Leftover MX on zone 7 does not consume aliases. It consumes trust.
Outgoing counts authenticated submits that 250. A retry after 250 is a duplicate, not capacity. A 550 does not spend the month the way operators hope. Design for the 250s you intend. IETF RFC 7208 — Sender Policy Framework (SPF) lookups are per send path, not a reason to buy Agency.
Step-by-step setup and decision path
List zones that will actually cut
Suite-hosted zones stay off the sheet. Dual MX is not capacity.
Multiply the noun list
hello, support, billing × zones. Add staffed extras only.
Add send-as events per month
Forms, receipts, one probe each. Not a list. Not warm-up.
Pick the card with headroom
Confirm pricing. Do not invent a middle tier.
Cut one zone and probe
Exclusive MX. Foreign probe. Then scale cuts, not guesses.
Re-count after intake changes
A new vertical extra is a capacity event. So is offboard.
Failure modes and proof
| What you see | Likely cause | Proof |
|---|---|---|
| Cannot create the fourth alias | Free cap | Quote a paid card |
| 550 on send-as | Free or unmapped From | Plan, not leftover MX |
| Hourly 4xx/limit | Loop or shared Friday blast | Stop. Isolate SMTP |
| HOLD full of invoices | Unstaffed billing@ | Intake, not more aliases |
| Store expired | 14-day Free window | Paid 90-day or faster review |
| Zone 7 still leftover MX | Cut skipped | Capacity did not fail. The cut did |
Proof is a dated spreadsheet, a named card, exclusive listings on cut zones, and probes. “We bought Agency” is not proof zone 7 is exclusive.
MailerZ workflow and product boundary
Inbound MX plus authenticated SMTP. Envelope SRS. Header From never rewritten. Not IMAP. Not a bulk ESP. Not an open relay. Unhosted send is 550 5.7.1. Seats operate the map. They are not mailbox seats.
Confirm every number on /pricing before a quote. We do not promise inbox placement because you bought Agency. We do not sell SOC 2. Store windows are recovery windows, not archives.
Cost, alternatives, and trade-offs
| Choice | What you get | What you give up |
|---|---|---|
| Agency after a spreadsheet | Headroom you can show | The romance of Free forever |
| Workspace × nouns × zones | A suite. Quote Google live | The Gmail they already use |
| ImprovMX cards | Their limits. Quote live | Our HOLD default if that was the job |
| Catch-all instead of nouns | Guesses land | A countable alias list |
Time is a line item. Counting on Tuesday costs less than a Friday 550. Leftover MX costs more than the next tier.
What to count
Domains that will publish exclusive MailerZ MX. Named aliases you will create, not strings you hope catch-all covers. Seats that must log in. Outgoing 250s you intend. Hourly bursts at launch. Store days if HOLD or failed hops matter.
Do not count parked domains you will not cut. Do not count Workspace zones. Do not count plus-tags as aliases. IETF RFC 5233 — Sieve Email Filtering: Subaddress Extension plus addressing is a Gmail filter, not a MailerZ alias.
Do not count “unlimited” marketing language from other hops as a plan. Unlimited aliases can be a distraction. We publish numbers. Confirm them.
Headroom is a decision
A fleet at 98 aliases on a 100-alias story is not Agency. Our Agency card is 500 aliases. Still leave room for one extra noun and one emergency alias. Headroom is cheaper than an emergency upgrade during an incident.
Hourly caps exist so a bug cannot become a campaign. If launch day sends twenty probes in a minute, you designed a loop. Capacity planning includes “one probe per noun,” not “retry until green.”
Shared SMTP across clients couples their hourly caps. Isolate credentials so one site cannot spend the fleet’s hour.
Staff time is capacity
HOLD without a reviewer is a full disk with extra steps. FORWARD catch-all without a reviewer is a spam cannon. Both consume humans. Put review on the same spreadsheet as aliases.
Two-factor on destinations. Re-query MX after website saves. IPv6 failures after exclusive names exist are host problems. Night operators who “just enable catch-all so we don’t need more aliases” trade a cap for noise.
If a second operator needs the order, send this page plus the naming-standard article. Count. Quote. Cut one zone. Probe. Re-count when intake changes.
The artifacts that close email routing capacity planning are a dated count, a named live card, and exclusive probes on the zones you claimed. Everything else is a guess you called a plan.
Field notes for capacity math
Count what you will actually cut
Domains that will publish exclusive MailerZ MX. Named aliases you will create. Seats that must log into the dashboard. Monthly outgoing 250s you intend. Hourly send-as bursts. Store days if HOLD or failed hops matter. Do not count parked zones you will not cut. Do not count Workspace zones. Do not count plus-tags as aliases. Plus addressing on Gmail is a filter, not a MailerZ alias.
Free is one domain, ten aliases, one seat, fourteen-day store, send-as disabled, hold unknowns. Solo is forty dollars a year, twenty-five aliases, ninety-day store, 2,500 outgoing, 20 send-as per hour. Starter is eight or eighty: eight domains, fifty aliases, five seats, 5,000 outgoing, 40 per hour. Business is nineteen or one hundred ninety: twenty-five / two hundred / twenty-five, 12,000 outgoing, 60 per hour. Agency is thirty-nine or three hundred ninety: one hundred / five hundred / fifty, 20,000 outgoing, 60 per hour. Confirm the live pricing page. Caps are not an inbox SLA.
Noun list times zones
hello, support, billing times ten sites is thirty aliases before extras. careers and press are extras you must staff. A noun list times a fleet will not fit Free. Collapse extras or change cards before you print. Catch-all is not extra cap and not a stealth pool. HOLD unknowns on everyday production.
Send-as is a second count. Forms, receipts, and one probe each. Not a list. Not warm-up. Hourly caps exist so a bug cannot become a campaign. Twenty probes in a minute is a loop you designed. Shared SMTP across clients couples their hourly caps. Isolate credentials.
Headroom is cheaper than a Friday upgrade
A fleet at the ceiling of a card is not a plan. Leave room for one emergency alias and one extra noun. Headroom beats discovering the cap during an incident. “We will upgrade if we hit it” is how launch day 550s happen.
Agency does not merge leftover MX. Zone seven with leftover Google is a cut failure, not a capacity failure. Buying Agency does not prove zone seven is exclusive.
Staff time is on the spreadsheet
HOLD without a reviewer is a full disk with extra steps. FORWARD catch-all without a reviewer is a spam cannon. Put review hours next to alias counts. Store windows are fourteen days on Free and ninety on paid. They are recovery windows, not archives and not eDiscovery.
Seats operate the map. They are not mailbox seats. Do not buy a suite seat per role string.
Wrong product class
Eight hundred outgoing on Agency is operational mail, not a campaign. Digests, newsletters, and purchased lists belong on an ESP. MailerZ is not a blaster. Unauthorized send is 550 / 550 5.7.1. Not SOC 2. Not HIPAA.
Worked story: sales promised careers, press, and a form send-as on Free. Launch day the fourth alias did not exist and the form 550’d. They quoted Starter from a spreadsheet, created the names, exclusive MX, probed, then enabled paid SMTP. The promise was the outage. The card was the fix.
Second story: an agency bought Agency and still left leftover MX on three client zones. Capacity looked fine. History on those zones was empty. They cut leftovers one zone at a time. Agency money did not delete Google hosts.
Operator brief: spreadsheet zones times nouns, plus extras, plus send-as volume. Quote the live card with headroom. Cut one zone. Probe. Re-count after intake or offboard. MailerZ can host the hop you paid for. It cannot invent aliases above the card. Start free on one zone. Agency when the math says the fleet is real.
Related: pricing, features, migration planner, delivery recovery, aliases and catch-all. Keep the dated count next to the named card. The next intake meeting should not restart at “Agency sounds big.”
Capacity is five numbers, not a feeling
Email routing capacity planning fails when a founder quotes “unlimited aliases” from a competitor card and then discovers MailerZ ceilings on Friday. Count five numbers against the live pricing page before you print a noun or wire a form. Domains. Named aliases. Seats. Monthly outgoing. Hourly send-as. Free is one domain, ten aliases, one seat, fourteen-day store, send-as disabled, unknowns held. Solo is forty dollars per year: twenty-five aliases, ninety-day store, 2,500 outgoing, 20 send-as per hour. Starter is eight or eighty: eight domains, fifty aliases, five seats, 5,000 outgoing, 40 per hour. Business is nineteen or one hundred ninety: twenty-five, two hundred, twenty-five, 12,000 outgoing, 60 per hour. Agency is thirty-nine or three hundred ninety: one hundred, five hundred, fifty, 20,000 outgoing, 60 per hour. Confirm those cards. They are ceilings, not an inbox-placement service-level agreement.
A domain is a zone you will publish exclusive MailerZ MX on. A parked name you never cut does not consume routing until you add it, but promising twelve client zones on Free is a lie. An alias is a named local-part you will staff. Catch-all is not a free alias mint. Hold unknowns on everyday production. Review the store. Promote a leftover only when a real person used it. Seats are people who can see the dashboard, not mailboxes. MailerZ is not IMAP. Destinations stay Gmail or Outlook.
Monthly outgoing and hourly send-as only exist on paid plans. Free cannot finish send-as. A contact form that needs From hello@domain is a Solo-or-higher problem before it is a plugin problem. Copy the dashboard host, port, and TLS pair together. Set From to an identity you created. Unauthorized send is 550 / 550 5.7.1. Do not paste a Gmail password into the form. Do not discover the hourly cap by blasting a list. This hop is not a campaign sender.
Store window is recovery for hops this layer saw. Fourteen days on Free. Ninety on paid. It is not an archive and not legal hold. If counsel wants eDiscovery, buy eDiscovery. Capacity planning that treats the store as a mailbox will fail a discovery request and a customer “find last month’s bounce” ticket on the same afternoon.
Headroom is a date, not a vibe
Quote the card that fits today plus a dated headroom. If you have eleven aliases on Solo, the twelfth named leftover is a plan conversation, not a catch-all toggle. If you send eighty messages this month on Solo, the next form spike wants Starter or a queue. Write the date you will revisit. Agencies should keep one row per client zone. Do not pour every client into one catch-all because the spreadsheet got long. Agency capacity exists so you can hold more domains and aliases. It does not replace a named list.
Staff time is the hidden sixth number. Hold review is minutes. Leftover MX cleanup is minutes. Two-resolver checks after every wizard are minutes. If you cannot staff hold review, do not enable catch-all forward. Paid forward belongs to a dated cutover. Fan-out of unknowns into two inboxes trains two spam buttons and burns dest reputation that is not yours to spend.
A capacity sheet that survives a sales call
Columns: zone, NS owner, public MX exclusive yes/no, named aliases printed, dest mailbox, send-as needed yes/no, monthly estimate, hourly peak, plan card, leftover MX saved as text, last probe subject. Fill it before the call. If leftover MX is no, stop talking about alias ceilings. Hop one is still someone else’s. Delete leftovers. Wait for TTL on 8.8.8.8 and 1.1.1.1. Probe from another mailbox. Self-send from Gmail to the same Gmail can hide a split.
A worked miss: an agency sold “unlimited client aliases” on Starter. Fifty aliases filled. The fifty-first leftover went to hold. The client thought mail vanished. History was empty for that local-part because it was unnamed and held. The fix was print the leftover, promote it, or upgrade. Catch-all forward would have trained spam. They upgraded to Business, named the leftover, and probed. That is capacity, not a dest outage.
A second miss: a founder on Free wired a password-reset From. 550. They opened ten new aliases thinking inbound maps mint outbound. Creating an inbound alias does not approve send-as. Catch-all does not mint a From. Solo at forty dollars per year was the honest next card. Confirm /pricing. Related runbooks live on features, send and reply, and the pricing page. This page is the count.
Envelope SRS only. Header From, Subject, Date, Message-ID, body, and MIME stay intact. MailerZ is not Workspace, not a hosted mailbox, not an open relay. Comparisons with a suite or a ciphertext store only help after the hop is honest. Cite the other product’s documentation. Do not invent feature parity. MailerZ is not SOC 2, not ISO 27001, and not HIPAA. Point questionnaires at the published security, privacy, terms, DPA, and subprocessors pages.
When to stay, upgrade, or buy a suite
Stay on the current card when named aliases fit, hold review is staffed, and send-as is either unused or inside hourly and monthly limits. Upgrade when a real person used a leftover you cannot name without blowing the ceiling, or when a form will exceed outgoing. Buy a suite seat when someone needs a hosted mailbox, Calendar, and admin on the domain — not because you printed support@. A suite MX and MailerZ MX together is split brain. Exclusive one owner.
Offboard is capacity too. Delete MX you own. Revoke SMTP. Stop forwarding leftovers into an agency inbox. Do not leave a client zone on your Agency card after the contract ends. The next physical action after this article is fill the five numbers, then a lookup and a probe, not another tab. Start free on one domain you can break. Sign in if the zone already lives here.
Review quarterly, or sooner after a nameserver move, a plugin swap, or a staff departure. That is how email routing capacity planning stays a runbook. Print the public list. If you cannot print it, you are not ready for production unknowns and you are not ready for a bigger alias ceiling.
Operator packet for a capacity spreadsheet
Columns that belong on the sheet
Zone, will-cut yes or no, suite-hosted yes or no, noun list, extras, alias subtotal, seats who log in, monthly 250s intended, peak hour send-as, HOLD reviewer name, store window needed, leftover MX present, last probe date. Sum alias subtotals. Compare to the live card. Leave headroom.
Do not put parked domains in the will-cut column. Do not put plus-tags in the noun list. Do not put campaign volume in monthly 250s. Eight hundred outgoing on Agency is operational mail. A newsletter is an ESP.
How to pick the card without folklore
Free: one domain, ten aliases, send-as disabled, HOLD unknowns. Solo: forty dollars a year, twenty-five aliases, 2,500 outgoing, 20 per hour. Starter: eight or eighty, eight domains, fifty aliases, 5,000 outgoing, 40 per hour. Business: nineteen or one hundred ninety, twenty-five domains, two hundred aliases, 12,000 outgoing, 60 per hour. Agency: thirty-nine or three hundred ninety, one hundred domains, five hundred aliases, 20,000 outgoing, 60 per hour. Confirm /pricing. Do not invent a middle tier. Do not copy ImprovMX numbers onto these cards.
If send-as is in scope, Free is already the wrong card. If ten sites times three nouns is thirty aliases, Free and Solo are wrong. If HOLD has no reviewer, you do not have capacity. You have a disk.
Intake and offboard as capacity events
A new vertical extra is a capacity event. So is offboard. Re-count the week you add press@ fleet-wide. Re-count the week you delete a client zone. Agency does not auto-clean leftover MX on the zone you forgot.
Shared SMTP is a hidden hourly coupling. Isolate per client or per app. A Friday blast on one site should not 4xx the rest of the book.
What “we bought Agency” does not prove
It does not prove zone seven is exclusive. It does not prove HOLD is reviewed. It does not prove send-as From names exist. It does not prove inbox placement. It does not prove SOC 2. Proof is the dated sheet, the named card, exclusive listings, and probes.
Related: pricing, features, migration planner, how to organize fifty aliases, twenty roles with three inboxes. Start free on one zone. Quote Agency when the sheet says the fleet is real.
FAQ
What is the safest way to handle email routing capacity planning?
Count domains, named aliases, seats, monthly outgoing, hourly send-as, and store window against the live pricing cards before you promise a noun list or a send-as integration. Free is 1 domain, 10 aliases, send-as/SMTP/API disabled, HOLD or reject unknowns. Agency is 100 / 500 / 800 / 25 per hour. Caps are not an inbox SLA. HOLD review is staff time.
Does this require a new mailbox?
No. Capacity here is routing capacity: zones, aliases, and authenticated send. Destinations stay Gmail or Outlook. Buy a suite seat only if someone needs a hosted mailbox on the domain.
Will it work with Gmail or Outlook?
Inbound works with exclusive MX and mapped aliases within the alias cap. Send-as needs a paid plan and stays inside hourly and monthly limits. Self-send is a bad gate. Confirm /pricing.
What DNS records are involved?
Capacity does not change DNS physics. Each zone still needs exclusive MailerZ MX, leftovers deleted, and outbound SPF/DKIM/DMARC if you send. See RFC 5321. Two zones never share one leftover Google row.
What should I test before production?
Spreadsheet the counts. Quote the card that fits with headroom. Cut one zone. Probe nouns. Send one authorized message if send-as is in scope. Do not discover the cap on a Friday blast.
Key takeaways
- Count domains, aliases, seats, outgoing, hourly, store days.
- Confirm /pricing. Do not invent tiers.
- Caps are not an inbox SLA. Not SOC 2.
- Noun list × zones is the alias math.
- Send-as is a second count. Free has none.
- HOLD review is staff time.
- Agency does not merge leftover MX.
- Headroom beats a Friday upgrade.
Conclusion and next action
If you route many domains, count before you print. MailerZ can host the hop you paid for. It cannot invent aliases above the card. Start free on one zone, Agency when the spreadsheet says the fleet is real.
Ready to count one zone
Start free with one domain, then quote the card that fits.
Inbound on Free. Agency when the math says so. Sign in if the domain is already there.
Review when intake, noun list, or pricing cards change. Author: MailerZ editorial, Secuno LLC.