How do I know if a company uses Strato?

Look up the domain's MX records. A first MX host ending in rzone.de means mail goes through Strato. The email provider lookup and MX lookup tools show it for any domain.

Are domains behind Strato catch-all?

Some are and some aren't; it depends on how each company configured Strato. A verifier can tell by offering a random address that can't exist: if the domain accepts it, the domain is catch-all and single addresses there can't be confirmed.

What is rzone.de in an MX record?

It is the STRATO mail host. STRATO's FAQ names smtpin.rzone.de as the MX record for its shared hosting mail.

Business mail platform · Strato

Verifying addresses at Strato domains

Can you verify addresses at domains behind Strato?

Depends on the domain

It depends on the company. Domains behind Strato are probed like any other.

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Strato answers for the company's own mail rules, so the checker treats every domain on its own: it offers a random address first, and if that is accepted the domain is catch-all and results come back risky ("Accepts all addresses"). Otherwise your address gets a per-mailbox answer. It always checks the syntax, the domain's MX records, disposable domains and role addresses such as info@ first.

Reasons you'll see in results:Mailbox existsMailbox not foundAccepts all addresses

Company domains whose MX records point at rzone.de are hosted at Strato. Strato documents a catch-all option, and where an admin turns it on every address at the domain looks deliverable. Our checker probes each domain on its own: it offers a random address that can't exist first, and a domain that accepts it comes back risky as catch-all; otherwise your address gets a per-mailbox answer.

Live DNS snapshot: strato-hosting.co.uk

Checked 25 October 2026, 08:03 UTC

rzone.de is an MX host suffix, not a mail domain, so this is strato-hosting.co.uk: a domain whose mail runs through Strato. Read from DNS at the time shown and refreshed at most once a day.

MX1 host

100fwmx.rzone.de

SPFPublished

v=spf1 a:ap4-p00-ob.smtp.rzone.de a:ap4-p02-ob.smtp.rzone.de a:ap4-p03-ob.smtp.rzone.de a:ap6-p00-ob.smtp.rzone.de a:ap6-p02-ob.smtp.rzone.de a:ap6-p03-ob.smtp.rzone.de include:_spf-corporate.ionos.com ~all

DMARCPublished

p=reject: meets the requirement and enforces it.

v=DMARC1; p=reject; pct=100; adkim=r; rua=mailto:strato-hosting_co_uk@dmarc-reports.strato-hosting.co.uk; ruf=mailto:processed@strato-dmarc.de

Look up any other domain with the MX lookup or the email provider lookup.

Strato at a glance

Operated by	STRATO GmbH, Otto-Ostrowski-Straße 7, 10249 Berlin, GermanySource: STRATO imprint (German)
MX hosts	`smtpin.rzone.de`Source: STRATO FAQ (German): DNS-Einträge verwalten
Address rule	A mailbox set as catch-all receives all mail sent to undefined addresses of the domain; one catch-all per domainSource: STRATO FAQ (German): E-Mail-Adressen einrichten
Address rule	Each new package comes with a preconfigured `webmaster` address with aliases `postmaster` and `abuse`Source: STRATO FAQ (German): E-Mail-Adressen einrichten

STRATO domains can be catch-all per domain

STRATO's DNS FAQ gives `smtpin.rzone.de` as the MX record for domains that keep using STRATO's shared hosting mail while DNS sits elsewhere.

STRATO documents a catch-all function: a mailbox ticked as catch-all receives mail to undefined addresses, one per domain. Where it is on, every address looks deliverable, so a person cannot be confirmed.

What our checker does behind Strato

SimpleVerifier doesn't skip or special-case Strato. For each company domain it offers a random address that can't exist, then your address, and disconnects without sending. If the random address is accepted, the domain is catch-all and its results come back risky with "Accepts all addresses". If it is rejected, your address gets a real answer for that mailbox.

Consumer mailboxes are a separate case; see the Gmail and Yahoo pages. Domains behind Strato are treated like any company domain.

Cleaning a list full of Strato domains

Split the list by domain, not by platform. Two companies on Strato can behave in opposite ways, so a catch-all result at one says nothing about the next. The bulk catch-all checker finds which domains in a list accept everything before you spend time on single addresses.

For catch-all domains, keep addresses with recent replies or sign-ups and send the rest in a small first batch, suppressing anything that hard-bounces. For per-mailbox domains, trust the verdict: invalid addresses will bounce, and valid ones were accepted by the company's own directory. Accept-all vs unknown results covers the difference.

Common questions

Can you verify addresses at domains behind Strato?: It depends on the company. Domains behind Strato are probed like any other. Strato answers for the company's own mail rules, so the checker treats every domain on its own: it offers a random address first, and if that is accepted the domain is catch-all and results come back risky ("Accepts all addresses"). Otherwise your address gets a per-mailbox answer. It always checks the syntax, the domain's MX records, disposable domains and role addresses such as info@ first.
How do I know if a company uses Strato?: Look up the domain's MX records. A first MX host ending in rzone.de means mail goes through Strato. The email provider lookup and MX lookup tools show it for any domain.
Are domains behind Strato catch-all?: Some are and some aren't; it depends on how each company configured Strato. A verifier can tell by offering a random address that can't exist: if the domain accepts it, the domain is catch-all and single addresses there can't be confirmed.
What is rzone.de in an MX record?: It is the STRATO mail host. STRATO's FAQ names smtpin.rzone.de as the MX record for its shared hosting mail.

Catch-all checkerTest whether a domain accepts any address before you trust a valid.

Bulk catch-all checkerFind the catch-all domains in a whole list at once.

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