Unknown recipient held means MailerZ accepted or stored a message for a local-part that is not a named alias, instead of forwarding it into your inbox or bouncing it immediately as you might expect. On Free, unknown mail is held. That is a safety default, not a broken domain. Add the alias if the local-part is real. Leave it held if it is noise. Do not switch catch-all to FORWARD just to feel busy.
Quick answer for unknown recipient held
Founders treat HOLD as an outage because the inbox is empty. The inbox is empty on purpose. Someone mailed a local-part you never published.
Free includes hold for unknown and forbids send-as. That pairing is intentional. You get three aliases. Use them. Do not demand a firehose.
Paid plans can FORWARD unknown. That is a trade: more accidental leads, more junk training. Audit it. Do not leave it on for a year unattended.
A 550 reject is the other unknown policy. It tells the sender immediately. HOLD keeps a copy in the store window so you can decide. Recovery pages exist for that window.
If the held local-part is a typo of hello@, add hello@ if missing and tell the sender the correct address. Do not FORWARD all typos forever.
If the held local-part is a role you want, create the role alias and map it to a person. Stability beats catch-all.
Authoritative mail transport is defined in IETF RFC 5321 — Simple Mail Transfer Protocol. Product path: aliases and catch-all, delivery recovery, and troubleshooting.
User problem and decision criteria
Decision criteria: is the local-part a real role, a typo, or a dictionary guess; is MX exclusive; is the store window still open; do you want the sender to get a bounce instead.
Criteria that do not belong: FORWARD everything, a new mailbox per guess, or turning off HOLD because a salesperson said “never lose a lead.”
Agencies should show clients the held list weekly at first. Pattern recognition is how you decide which aliases to create.
If HOLD is full of password-reset noise for accounts you do not have, you are seeing the internet scan your zone. That is why HOLD exists.
If a customer swears they mailed support@ and you see it held, you forgot the alias. Create it. Apologize. Do not blame MX.
If you see the message at an old host and also held, you still have leftover MX plus a MailerZ hold. Clean MX.
Legal sometimes wants every unknown message. That is a retention and privacy conversation, not a default FORWARD. Held mail still sits in a store with a clock.
Do not invent HIPAA or SOC 2 coverage for held messages. The security page states the control set. No badges.
Technical mail flow
Inbound MX, local-part lookup. Hit: forward with SRS envelope and intact headers. Miss: HOLD on Free, or configured paid behavior.
Held items are visible in the product during the store window. Fourteen days Free. Ninety paid.
Mapping later does not rewrite the past unless you recover inside the window. Do not assume old held mail will appear in Gmail automatically after you add the alias. Check recovery behavior in the app, not in this sentence as a new promise.
Senders may not get a bounce while you hold. That surprises people who expected 550. Explain it once in your runbook.
Catch-all FORWARD skips HOLD and dumps into the destination. The destination then files junk. You traded visibility for noise.
Step-by-step setup / decision path
- Open the held item. Copy the local-part and the sender.
- Decide: real role, typo, or scan.
- If real, create a named alias and map a destination. Probe it.
- If typo, create the intended alias if needed and tell the sender.
- If scan, leave HOLD. Do not FORWARD.
- Confirm exclusive MX so holds are complete, not split.
- Review the held list on a schedule. Do not live in it.
- Refuse catch-all FORWARD as a first response to any held item.
Write the decision on the ticket so the next person does not FORWARD the same noise tomorrow.
If the window expired, ask the sender to resend to the new named alias. Do not pretend the store is infinite.
Teach sales that HOLD is a feature. Leads that guess random addresses are not a pipeline.
Failure modes and proof
FORWARD to silence HOLD: junk cannon. Proof: random local-parts in Gmail.
Customer mailed a missing role: held, angry. Proof: add the alias.
Leftover MX: some unknowns never held here. Proof: public MX.
Expired store: no copy. Proof: timestamps. Ask for a resend.
Treating HOLD as downtime: wasted DNS. Proof: named aliases still work.
Null MX plus HOLD confusion: you are not receiving. Proof: public MX.
Privacy panic: dumping held mail into Slack. Proof: you just spread addresses. Use the product, not a screenshot dump.
Open relay to “accept all”: 550. Not available.
Buying seats for guesses: cost without a map.
Ignoring scans: then enabling FORWARD. Proof: next day’s junk.
Two people adding overlapping aliases: duplicate maps. Proof: the sheet.
Promising every held message will be recovered after expiry: false. The clock is the clock.
MailerZ workflow and product boundary
MailerZ is custom-domain aliasing and forwarding with optional paid send-as. Secuno LLC operates mailerz.net. The app is mail.mailerz.net. Not Workspace, not IMAP, not an open relay, not a campaign ESP.
Envelope SRS only. Header From, Subject, Date, Message-ID, body, and MIME stay intact. Exclusive MX. Hold unknown on Free. Copy SMTP host, port, and TLS or STARTTLS from the dashboard when you send. Do not invent 587 or 465 as MailerZ facts.
Free: one domain, three aliases, one seat, fourteen-day store, fifty outgoing a month, no send-as. Solo forty dollars a year, fifteen aliases, ninety-day store, one hundred outgoing, five send-as per hour. Starter eight monthly or eighty yearly. Business nineteen or one hundred ninety. Agency thirty-nine or three hundred ninety. Quote the pricing page. No SOC 2, ISO, HIPAA, SLA, or inboxing percentage.
HOLD on Free is a published default. Paid FORWARD is optional. Aliases and catch-all documentation is the hub for this decision.
Cost, alternatives, and trade-offs
HOLD is cheaper than a burned destination inbox.
Creating three good aliases on Free is cheaper than FORWARD noise.
Agencies should bill alias design, not catch-all babysitting.
A bounced 550 can be cheaper than holding forever if you do not want the copy. Know which policy you chose.
Workspace does not replace HOLD. It is a different product.
If sales demands FORWARD, price the junk cleanup in the same quote.
Store windows are a cost of delay. Decide while the copy exists.
Do not pay a second forwarder to HOLD less carefully.
Living with HOLD without turning it into FORWARD
Schedule a held-mail review. Daily in week one of a new domain. Weekly after that. Monthly when the list is only scanners. Unscheduled panic reviews are how FORWARD gets enabled at 11 p.m.
Tag held items: role we forgot, typo of a real alias, password-reset scan, vendor using a guessed address, leftover marketing campaign. Only the first two deserve a new named alias. The rest deserve HOLD.
When sales wants every held item forwarded “just in case,” show them a week of dictionary local-parts. Then show what that would do to Gmail. Price junk cleanup in the same conversation.
When a customer used support@ and you never created it, that is your miss. Create it. Recover inside the window if the product still has the copy. Apologize. Do not blame HOLD. HOLD did the safe thing with an unpublished address.
Explain to frequent senders that unknown local-parts may not bounce immediately. Some people treat a missing bounce as “it must have arrived.” Your status FAQ should say otherwise.
Exclusive MX matters for HOLD completeness. If leftover Microsoft MX still answers some senders, those unknown messages never enter your held list. You will think HOLD is empty while another host rejects or junks.
Do not paste held messages into Slack as a workflow. You are spreading addresses and bodies. Use the product and a named reviewer.
Free’s three aliases are a design constraint. Choose hello, billing, and a personal role. Do not waste them on experiments you will abandon. Paid plans exist when the sheet is longer. Quote pricing.
If you later enable FORWARD on paid, write an expiry date on that setting. Catch-all without an expiry becomes folklore. Review the destination junk rate on that date.
Recovery after mapping is not a time machine past the store window. If the copy expired, ask for a resend to the new named alias. Say that out loud so nobody invents infinite retention.
Legal hold fantasies are out of scope. MailerZ is not an archive product. Fourteen or ninety days is the published store, not a compliance vault. No HIPAA story.
Teach new staff that an empty inbox plus held items is often a healthy domain being scanned. Panic is optional.
HOLD is a missing name, not a down hop
Unknown recipient held means MailerZ accepted the conversation far enough to apply recipient policy and kept the message because the local-part is not a named alias and Free (or your chosen policy) holds unknowns. It is not leftover MX. Leftover MX never creates a hold row. Empty history is leftover or no arrival. A hold row is proof the hop ran and the name was unknown.
Free holds unknowns. That is the product. Catch-all FORWARD is paid and optional. Turning FORWARD on so “holds go away” hides the next missing printed name and dumps typos into Gmail. Create the local-part you actually print. Then decide FORWARD as a later choice, not as a debugger.
If the hold is a name you thought you created, you created a different spelling. hello versus Hello does not matter the way you hope if the UI stored something else. Diff the alias list against the hold’s recipient. Create the exact string. Re-probe from another mailbox. Self-send can hide whether the hold still happens.
Plus-looking tags are not aliases unless you created them. MailerZ does not claim to strip plus tags on custom domains. founder+stripe@ on a hold is a string you never named, or a leftover path. Print billing@ and create billing@.
Plan math: three holds on Free may mean you printed six names. Solo is fifteen. Starter is fifty. A hold storm is often undersizing, not an outage. Do not buy Workspace seats to clear holds. Destinations are Gmail. Names are aliases.
Exclusive MX still matters. If some senders hit leftover Google MX, they never HOLD. They land in a Group. You will think HOLD is flaky. Two resolvers. Delete leftovers. Then read holds as a complete set.
Retention: 14 days Free, 90 paid. Export a hold you still need. After the window the destination never got a copy — that is the point of HOLD. If you needed the body, you needed the named alias yesterday.
Do not republish MX to “release” a hold. Create the alias or reject the name. MX does not invent local-parts. SPF does not either.
Send-as is unrelated. Free cannot send. A 550 From is not a hold. Do not mix the tickets.
Header From on a held item stays the original sender. Envelope may show SRS after forward once you create the alias and the next message flows. We do not rewrite Header From to make holds look local.
What to do in order when the dashboard says held
One: copy the recipient string and the time. Two: two-resolver MX. If leftovers, stop and delete them. Three: diff aliases. Four: create the name or decide it stays unknown. Five: if you created it, probe from another mailbox with a unique subject. Six: if you did not create it, stop printing it. Seven: FORWARD only if you meant catch-all as a paid product, not as step four.
Customer ticket: “we emailed billing@.” Hold row on billing@ means create billing@. Empty history means leftovers or they sent elsewhere. Destination 5xx means Gmail refused after accept. Name the class in the first sentence.
Agencies: do not enable FORWARD on a client to clear a hold list you never triaged. That list is the map you were hired to build.
Security@ and jobs@ holds are how people learn they printed a name on a PDF and never created it. Create before the next researcher or applicant. Do not FORWARD the domain to be polite.
If holds are spam guesses, good. HOLD is doing the job. Creating every guess is sprawl. Solo 15 and Starter 50 exist so you choose. Museum names get dropped on purpose.
After you create the alias, old held copies do not automatically become a destination thread unless the product still has them inside the window and you recover per the UI. Do not assume Slack will get a replay. Ask the sender to resend if the window is tight.
Night CTA: start free — one domain — if you need to see HOLD work on three names. Upgrade when the fourth printed name is real. Paying does not delete leftover MX.
No inbox SLA on a released hold. Gmail still files the next message. We do not sell Primary. No SOC 2 sentence. /security for controls.
Monthly: leftover MX, hold list versus letterhead, alias count versus plan. Five minutes. The outage you avoid is FORWARD-all after a single angry hold.
Self-send to a held name can short-circuit. Use another mailbox. The hold row from a stranger is the only valid lesson.
HOLD is a missing name, not a broken internet
Unknown recipient held means the hop accepted the message because MX pointed here, then refused to invent a destination you never created. On Free, catch-all is HOLD. The mail is stored for fourteen days. It is not forwarded to a guess. It is not bounced as user unknown at the first hop if the product holds it. Your job is to decide whether that local-part should exist, should stay unknown, or was a typo you will never bless.
People treat HOLD like leftover MX because both can feel like “mail disappeared.” They are opposites. Leftover MX means another host answered. History on MailerZ is empty because the message never arrived. HOLD means history exists and the name is not in your alias list. If you restore Google MX because you saw HOLD, you will lose the next invoice to a host you are not watching. Read the event. Then act.
The first question is whether the sender used a name you print. support@, hello@, the founder’s first name. If yes, create the alias and, on paid, decide whether you replay or ask for a resend. Fourteen days on Free is a clock, not a promise that you will notice. Check HOLD daily during the first week after a cut. After that, check when a human says they sent something.
The second question is whether the name is attacker noise. Random strings, credential stuffing local-parts, and old employee names from a leaked list will HOLD on Free if MX is exclusive. That is useful. You see the probe. You do not forward it into Gmail. Do not create aliases for noise. Do not enable paid FORWARD to “make HOLD go away.” FORWARD is a policy for names you accept. Noise should stay held or rejected by policy, not delivered.
Paid catch-all FORWARD is a different product choice. It delivers unknown local-parts to a destination you picked. That hides the map. It also delivers typos to a human. Use it when you understand the spam cost. Do not use it on cut day to avoid creating three invoice names. Create the names. HOLD on Free is the training wheels that show you what the internet still thinks you own.
Destination 5xx after a 250 at the hop is not HOLD. The alias existed. The hop tried Gmail or Outlook. The mailbox rejected. Full mailbox, blocked sender, and policy on the destination are restores on that side. Copy the SMTP line. Do not delete the alias. Do not republish leftover MX. Do not file HOLD as the category in your notes. Wrong category is how the next on-call repeats the wrong fix.
Empty history is not HOLD. Empty is leftover MX, a name that never hit this host, or a sender still cached on old MX. Probe from a stranger mailbox to the same local-part. If the probe HOLDs, you now have a name to create. If the probe is empty, you still have a leftover or a cut that never finished. Those tickets should not share a title.
Vault and HOLD are easy to mash together in conversation. Vault is stored mail you can open under the product’s store window. HOLD is why an unknown name sat instead of forwarding. Opening Vault does not create an alias. Creating an alias does not require calling it a mailbox. MailerZ is not IMAP. Do not tell a customer they have a new inbox because HOLD showed a message. Tell them the hop kept a copy until you named a destination.
Seats and aliases are different knobs. One seat can own several aliases. HOLD does not mean you are out of seats. It means that local-part is not in the list. Free: three aliases. Solo: fifteen. Starter: fifty. If HOLD is a fourth invoice name on Free, upgrade or stop printing the fourth name. Do not ask the hop to guess.
Replay is a paid operational choice when the product offers it. If you cannot replay, ask the sender to resend after you create the alias. Do not pretend a Gmail search will find a message that only existed on HOLD. The destination never saw it. That sentence is the whole support script.
Write HOLD in the runbook as a success state for unknown names on Free. The cut worked. MX is exclusive. The map is incomplete or the sender invented a string. Incomplete map is an alias ticket. Invented string is ignore or block. Leftover MX is a DNS ticket. Keep the three tickets apart and Friday gets quieter.
Facts: Free HOLD, fourteen-day store, no send-as. Paid can FORWARD unknowns if you enable it, ninety-day store. Envelope SRS. Header From intact. Not SOC 2. Start free if you want HOLD to teach you the names you forgot to create. Sign in when the domain already lives on the hop.
FAQ
- What is the safest way to handle unknown recipient held?
- Read the local-part in history. If a human should own it, create a named alias. If it is a guessed address, leave HOLD. Do not FORWARD all unknown mail to “catch leads.” That is how destinations become spam cannons.
- Does this require a new mailbox?
- No. Holding unknown mail is the opposite of buying seats. MailerZ is not IMAP.
- Will it work with Gmail or Outlook?
- Held mail does not enter those inboxes until you map it. That is the point. After you map, a probe should arrive.
- What DNS records are involved?
- MX must be exclusive so the hold you see is MailerZ’s hold. Leftover MX can make some unknown mail land at an old host instead.
- What should I test before production?
- Send to a named alias and to a deliberately fake local-part. The fake should hold, not appear in Gmail. The named should arrive.
Key takeaways
- Unknown recipient held is a default, not an outage.
- Add named aliases for real roles.
- Leave scans held. Do not FORWARD to feel busy.
- Exclusive MX so holds are complete.
- Store windows expire. Act inside them.
- Free: three aliases, HOLD, no send-as.
- Paid FORWARD is a trade, not a virtue.
- Explain to senders if they expected an immediate bounce.
Conclusion
Read the local-part. Map what you own. Hold what you do not. That is the whole job.
Start free with one domain and send a fake local-part on purpose. Confirm it stays held. Then you understand the product.