How to prevent email forwarding loops

Quick answer for prevent email forwarding loop

Point each alias at a mailbox that does not auto-forward back to that alias. Hold unknowns. Exclusive MX. That is prevent email forwarding loop.

Guide: dest is a store. Setup: named maps, no dest-side forward to the domain. Best practice: one hop owner.

SRS rewrites envelope MAIL FROM. It is not a loop license.

Two dests that both forward to each other will still loop.

MailerZ Free is one domain, three aliases, one seat, a 14-day store, send-as disabled, SMTP and API disabled, and unrouted mail held or rejected only. Solo is $40 per year only. Starter is $8 monthly or $80 yearly. Business is $19 or $190. Agency is $39 or $390. Unlimited is $99/month or $990/year. Confirm numbers on MailerZ pricing. Limits are not an inbox-placement promise.

Google’s own Send mail as steps live in Google Gmail Help — Send mail from a different address. Workspace as a product is described on Google Workspace — product overview. Transport still follows IETF RFC 5321 — Simple Mail Transfer Protocol.

prevent email forwarding loop guide: the real decision

Gmail filter forwarded back to hello@domain.

Catch-all to a hop that catch-all’d back.

Leftover MX plus MailerZ both forwarding.

Criteria: dest is a store, no back-forward, hold unknowns, exclusive MX.

Technical mail flow for prevent email forwarding loop

Accept, map, dest SMTP. If dest injects the same RCPT back, hop repeats.

Leftover MX plus MailerZ can bounce copies between operators.

Header From may look fine while the envelope cycles.

Hold stops unknown local-parts from joining the cycle.

MailerZ is inbound MX plus authenticated SMTP from Secuno LLC. Envelope SRS only. Header From, Subject, Date, Message-ID, body, and MIME are never rewritten. Not Google Workspace, not IMAP, not webmail, not an open relay. Unauthorized send is SMTP 550 / 550 5.7.1. Leftover MX is a hard stop. Self-send from Gmail to the same Gmail account can hide routing errors. Not SOC 2, not ISO 27001, not HIPAA.

prevent email forwarding loop setup

List dest-side forwards and filters before you print the alias.

1. Create named aliases to stores people open.
2. Disable Gmail/Outlook auto-forward back to the domain.
3. Hold unknowns. Do not catch-all two hops.
4. Exclusive MailerZ MX. Delete leftover forwarder MX.
5. Probe a unique subject. Watch history for repeats.
6. If a loop appears, disable dest forward first, then remap.
7. Do not enable send-as to “break” a loop.
8. Agencies: per-zone dest-forward audit.

Failure modes and proof

Dest-side forward forgotten.

Dual MX two forwarders.

Catch-all hose.

Self-send as the only test.

Shared dest that forwards everything.

MailerZ workflow and product boundary

Related: features, security, aliases and catch-all, send and reply.

Not a loop-prevention SLA. History shows hops we saw.

Related pages: features, security, aliases and catch-all, and send and reply.

prevent email forwarding loop best practice

A loop burns outgoing caps and dest quota. Confirm /pricing. Stop the dest forward. Do not buy more aliases to outrun a cycle.

Google helpful-content is for pages. Name hops anyway.

MailerZ Free is one domain, three aliases, one seat, a 14-day store, send-as disabled, SMTP and API disabled, and unrouted mail held or rejected only. Solo is $40 per year only. Starter is $8 monthly or $80 yearly. Business is $19 or $190. Agency is $39 or $390. Unlimited is $99/month or $990/year. Confirm numbers on MailerZ pricing. Limits are not an inbox-placement promise.

Field notes you can reuse

Compromised-alias disable is a sibling.

Auth is not encryption — next-but-one.

SRS is inbound envelope.

14-day store may show the cycle if we accepted it.

SOC 2 is still no.

Do not invent a loop-kill feature name.

Quarterly dest-forward audit.

Legal@ dests must not auto-forward home.

Deeper field notes for prevent email forwarding loop

The dest is allowed to be boring

Prevent email forwarding loop by treating Gmail or Outlook as a store, not as another forwarder. Auto-forward, plus-address tricks that bounce home, and “forward all to the domain” filters are how cycles start. MailerZ maps a named alias to that store. If the store sends the copy back to the same RCPT, hop two repeats. History fills. Caps burn. Dest quota dies.

Catch-all to a second hop that catch-alls back is the agency version. Hold unknowns. Exclusive MX. One hop owner. SRS rewrites envelope MAIL FROM. It does not bless a loop. Header From may look fine the whole time.

How to see a loop

Same unique subject repeating in history. Same Message-ID family bouncing. Disable dest-side forward first. Do not remap twenty aliases. Do not enable send-as to break a loop. Do not delete MX.

Leftover MX plus MailerZ

Two operators both accepting and forwarding can pass copies around. Delete leftovers. That is loop prevention and leftover hygiene. Related: features, security, aliases and catch-all, send and reply.

Google helpful-content is for pages. Name the dest filter anyway. Not SOC 2. Confirm /pricing if a loop burned the month.

A complete worked story

The Gmail filter that mailed home

hello@ forwarded to founder Gmail. A filter sent anything with the domain back to hello@. History filled with repeats. They deleted the filter, held unknowns, probed a new subject, and the cycle died. The hop was fine. The dest forward was the loop.

Operator brief

A longer operator brief for prevent email forwarding loop

Teams that bookmark How to Prevent Email Forwarding Loops usually arrive after a missed invoice, a form that never notified anyone, or a migration that looked clean in one resolver. The useful brief is still boring. Name the store. Name the printed local-parts. Name the nameservers that actually answer. Publish one MailerZ MX set. Delete leftover hosts. Probe from a mailbox that is not the destination. Only then talk about prevent email forwarding loop as a send-as, catch-all, or comparison problem.

MailerZ remains inbound MX plus authenticated SMTP around Gmail or Outlook. Envelope SRS only. Header From, Subject, Date, Message-ID, body, and MIME stay intact. It is not a hosted mailbox, not IMAP, not webmail, and not an open relay. Unauthorized send is 550 / 550 5.7.1. Free cannot finish send-as: SMTP and API stay off. Solo is $40 per year when the domain From must travel. Starter is $8 or $80. Business is $19 or $190. Agency is $39 or $390. Unlimited is $99/month or $990/year. Confirm the live pricing page. Those numbers are ceilings, not an inbox-placement service-level agreement.

If leftover Google, Microsoft, Cloudflare routing, or registrar MX is still public, stop widening prevent email forwarding loop. The map you built never saw that copy. Priority numbers are an order, not load balancing. A higher preference host is idle while a leftover host still accepts mail. Save the old MX set before you delete anything. Check more than one public view because TTL lies.

Catch-all forward is not a safety feature for how to prevent email forwarding loops. Hold unknowns on everyday production. Review the store. Promote a leftover only when a real person used it. Paid forward belongs to a dated cutover. Fan-out of unknowns into two inboxes trains two spam buttons. Plus addressing on Gmail is not a custom-domain unknown policy. MailerZ will not strip plus tags on your domain the way Gmail does on @gmail.com.

Send-as is a second hop. Creating an inbound alias does not approve outbound. Catch-all does not mint a From. Copy the dashboard host, port, and TLS pair together. Set From to an identity you created. Do not paste a Gmail password into a CMS, a cron file, or a ticket. Do not mail SMTP secrets to support. Send a 550 line, a timestamp, and a Message-ID. Rotate if a secret already leaked.

Self-send from Gmail to the same Gmail account can short-circuit. That green result is why people swear prevent email forwarding loop works while customers vanish. Use a second provider. Put a unique subject on the probe so delivery history is searchable. If Header From was rewritten by some other forwarder, authentication stories get noisier. MailerZ does not rewrite Header From on inbound.

Agencies should keep prevent email forwarding loop per client zone. Separate SMTP credentials. Do not pour every client into one catch-all because the spreadsheet got long. Agency plan capacity exists so you can hold more domains and aliases. It does not replace a named list. Offboard means delete MX you own, revoke SMTP, and stop forwarding leftovers into the agency inbox.

Legal and security questions have published answers on the security, privacy, terms, DPA, and subprocessors pages. MailerZ is not SOC 2, not ISO 27001, and not HIPAA. The 14-day Free store, the 90-day Solo–Agency store, and the 180-day Unlimited store are recovery windows for hops this layer saw. They are not an archive and not legal hold. If counsel wants eDiscovery, buy eDiscovery.

Comparisons only help after the hop is honest. Cloudflare Email Routing is inbound routing. A privacy-mask product hides a destination on a provider domain. A suite hosts mailboxes, Calendar, and admin. Proton-class mailboxes encrypt a store. MailerZ is the delivery layer when you already have Gmail or Outlook and you need a domain route you can prove. Cite the other product’s documentation. Do not invent feature parity.

When How to Prevent Email Forwarding Loops is closed, the next physical action is 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 prevent email forwarding loop stays a runbook instead of an incident.

A second worked pass for prevent email forwarding loop: write the last change on a sticky note before you open the dashboard. Nameserver move, leftover MX, new form plugin, contractor laptop, or a registrar forwarding toggle are the usual five. MailerZ history only shows hops that reached this layer. If the sticky note says leftover MX, you do not have a prevent email forwarding loop mystery. You have a split. Delete the leftover. Wait for TTL. Probe again.

A third worked pass: 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. Unlimited aliases as marketing will not save a missing list. Three named aliases on Free are enough to stop printing a personal Gmail on a homepage. Grow the list when a real person used a leftover, not when a harvest guessed admin@.

The dest must not point back at the public name

Prevent email forwarding loop failures by making the destination a mailbox you control that does not forward back to the public alias. The usual loop is alias hello@domain to a Gmail that has a filter “forward to hello@domain.” The second usual loop is two providers pointing at each other during a parallel cut. The third is catch-all fan-out into a dest that re-injects unknowns. Named aliases. Hold unknowns. Exclusive MailerZ MX. One dest you can open.

MailerZ envelope rewrite is SRS only. Header From, Subject, Date, Message-ID, body, and MIME stay intact. A loop that rewrites Header From somewhere else is a different product. We will not strip plus tags on your domain. We will not invent a loop-break header story you cannot print. If you see the same Message-ID cycling, stop the dest forward first. Do not add a second dest “for safety.” Two dests that both bounce back is two loops.

Catch-all forward is how loops hide. A harvest hits random local-parts. Each unknown fans out. A dest filter forwards “everything from this domain” back to the domain. Volume explodes. Hold unknowns on everyday production. Review the store. Promote a leftover only when a real person used it. Paid catch-all forward belongs to a dated cutover, not a permanent safety blanket.

Parallel providers

Running old and new MX at once is split brain, not a loop by itself. It becomes a loop when the old host forwards to the new public name and the new host forwards to a dest that still uses the old host. Exclusive MailerZ MX. Delete leftovers. If you must run a dated parallel, name the dest mailbox, disable dest-side forwards to the public alias, and keep unknowns held.

Agencies: one dest mailbox per client role, not one agency inbox that auto-forwards back to every client domain. Offboard means delete MX you own and disable dest forwards you asked the client to create. Cite Google’s helpful-content guidance when you write public docs about this. Do not invent a certification.

A loop that looked like a spam spike

A site printed support@ to a Gmail. Gmail forwarded “all mail from the domain” back to support@ so a contractor could see it in a second tool. MailerZ accepted, forwarded, dest forwarded, MailerZ accepted again. History filled with the same subjects. The operator thought they were under attack. The fix was disable the Gmail forward, keep the named alias, hold unknowns, and send one new probe from another mailbox. Volume dropped on the next TTL window. No new aliases were required.

A second case used catch-all into two dests. One dest had an autoresponder to the envelope sender. After SRS, some autoresponders still find a path back. Disable the autoresponder on the dest during the investigation. Do not disable the whole domain. Neighbor aliases should keep working.

Related: features, security, aliases and catch-all, send and reply. This page is the loop. The next action is print dest forwards and turn the circular one off.

Dest settings to print before you blame MX

Open the destination Gmail or Outlook. List every forward, filter that forwards, and inbox rule that resends. If any target is the public alias or the domain catch-all, turn it off. Autoresponders that mail the envelope sender can re-enter after SRS. Disable the responder while you prove the loop. Vacation replies on a dest that receives fan-out are a common amplifier.

Print MailerZ dests for that alias. One dest you can open is enough. Two dests that both forward “back to the domain” is two loops. Catch-all plus a dest “forward all from this domain” is how harvest becomes a storm. Hold unknowns. Named aliases only.

Exclusive MX still matters. A leftover host that also forwards to the public name is a loop you cannot see in MailerZ history until hop one randomly lands here. Delete leftovers. Two resolver views. Then one new subject from a mailbox that is not the dest. If volume dies, you were looping, not under a new campaign.

Confirm /pricing when you need more named aliases so you can stop using catch-all as a crutch. Free has three. Solo has fifteen. The list is the control. Related: features, security, aliases and catch-all, send and reply. Google’s helpful-content guidance is the external for how you write this runbook in public — dofollow, no invented certs.

What MailerZ will not do to “break” a loop for you

We will not rewrite Header From to hide the public name. We will not strip the dest forward. We will not turn catch-all off from a guess. You disable the circular dest rule. You hold unknowns. You keep exclusive MX. If you want a product that rewrites bodies to break loops, that is a different hop and you must cite that vendor. Confirm /pricing for named-alias headroom so catch-all can stay off.

FAQ

What is the safest way to handle prevent email forwarding loop?

Map each alias to a mailbox that does not auto-forward back to that alias. Hold unknowns. Publish exclusive MailerZ MX. Delete leftover forwarder hosts. If a loop starts, disable the dest-side forward first. Do not catch-all two hops at each other.

Does this require a new mailbox?

No. MailerZ is not IMAP and not webmail. Gmail or Outlook remains the store unless you separately buy a hosted mailbox product.

Will it work with Gmail or Outlook?

Yes for inbound when the destination is a verified mailbox. Branded replies need paid send-as plus Gmail Send mail as or a manual Outlook SMTP identity. Free has no send-as.

What DNS records are involved?

A verification TXT, one MailerZ MX set on the authoritative nameservers, leftover host MX removed, and SPF, DKIM, and DMARC if you also send as the domain.

What should I test before production?

Send a uniquely titled message from an unrelated provider into each named alias. Confirm Header From and delivery history. Do not email yourself from the same Gmail account.

Key takeaways

• Dest is a store.
• No back-forward.
• Hold unknowns.
• One MX owner.
• Watch history repeats.
• Kill dest filter first.
• No dual forwarders.
• Probe unique.

Conclusion and next action

Prevent forwarding loops by mapping aliases to stores that do not send the copy home. MailerZ is one hop. Catch-all and dest-side forwards are how cycles start. Exclusive MX. Hold unknowns. Audit filters.

Start free. Sign in if history shows the same subject repeating.

Review quarterly, or sooner if Gmail, Workspace, or MailerZ scope changes. Author: MailerZ editorial, Secuno LLC.