Hard vs. Soft Bounces in Yandex 360 and Mail.ru

Learn how to interpret hard and soft bounces from Yandex 360 and Mail.ru, protect sender reputation, and pause campaigns at the right time.

A hard bounce means the address or domain is no longer usable: the mailbox does not exist, has been disabled, or its domain cannot receive mail. Remove it from future outreach immediately. A soft bounce means delivery was deferred or refused for now; it may be a recipient-side issue, but it can also be the first visible sign that Yandex 360 or Mail.ru does not trust your sending setup.

For campaigns into Russia and CIS, do not rely only on the “hard” or “soft” label in your sending platform. Yandex 360 and Mail.ru are major business inbox providers, and their response text, timing, and repetition matter more than a simplified dashboard status. One temporary refusal calls for patience. Similar refusals across several addresses at the same provider call for a campaign pause and a sender-side check.

First, separate a bounce from silence and an opt-out

A bounce is a technical response returned to your mail server. You may see it in delivery logs, a non-delivery report, or your outreach platform. A delivered email that receives no reply is not a bounce. The reason could be weak targeting, an unclear offer, a poor subject line, or placement in Spam rather than Inbox.

A human reply such as “not interested,” “do not contact me,” or “remove my details” is also not a bounce. Treat it as an explicit opt-out: add the contact to a suppression list and stop that sequence. In Russian B2B, owners and commercial leaders often read business mail themselves, so a relevant, specific approach is quickly distinguishable from bulk promotion.

Promotional email requires particular care in this market. The practical operating standard is simple: contact a business for a clear business reason, make the relevance of your offer easy to understand, and give the recipient a straightforward way to stop further messages. Use public corporate contacts where possible, avoid speculative address guessing, and honour a removal request immediately. For message structure, see How to Write a Cold Email That Does Not Read Like an Ad.

Read the code and the delivery text together

As a starting point, 5xx responses usually indicate a persistent failure and 4xx responses a temporary one. But the code alone is not the verdict. A 4xx response can mean a full mailbox, a receiving-server limit, or a protection layer declining mail from your particular sender.

Keep the original error text with the date, recipient address, recipient domain, sender domain, and campaign name. This field log turns scattered notifications into evidence: poor list quality looks different from a sender-reputation problem.

Addresses to remove without debate

If the response clearly says that the mailbox, user, or recipient does not exist, remove it. Retrying a non-existent address does not create an opportunity; it only lowers the quality of your list.

The same applies to a non-existent domain after you have checked for a likely typo. A single extra character in a company domain can create a hard bounce. If the domain truly has no mail service, suppress all contacts associated with it rather than testing variations.

A disabled mailbox should not trigger automatic guessing of name.surname@, info@, or other common formats. Find a current channel on the company website or in public corporate sources first. In Russia and CIS, large international data platforms may have limited coverage or availability, so verification work often relies more heavily on company sites, public registries, and manual review.

If a meaningful share of a newly collected segment hard-bounces, treat this as a list-building incident, not a Yandex 360 or Mail.ru issue. Revalidate the source before increasing volume. Our field note on validating an email list before cold outreach in Russia covers the checks to run before the next launch.

Soft bounces: wait, quarantine, or stop

A temporary refusal is not permission to retry forever. Set a short protocol in advance: defer delivery, check the next result, then quarantine the contact after a limited number of equivalent failures. The exact interval depends on your infrastructure, but repeated delivery attempts to an address that asked you to wait are rarely productive.

An isolated soft bounce across unrelated domains is often a mailbox or receiving-server condition. A cluster of similar bounces from Yandex 360 or Mail.ru within a short period is different. At that point, the campaign is providing reconnaissance on your sender configuration and reputation.

Compare what changed before the pattern appeared: sending volume, a new sending domain or mailbox, a revised template, additional links, attachments, list source, or mail provider. Also compare the pair of sender domain and campaign. If one domain receives policy-style refusals while another sends a similar volume without them, focus the investigation on the affected sending environment.

When a bounce is really an anti-spam signal

Filters do not always state their decision plainly. They may mention policy, unwanted content, suspicious activity, or receiving limits. In other cases, the mail is technically accepted and placed in Spam, which produces no bounce at all. Delivery failures and poor inbox placement require different checks, but they point to the same operational object: whether recipients’ providers trust your sender.

Do not answer a suspected filter by raising volume, rotating random addresses, or rewriting subject lines every few minutes. Pause first. Then check:

• SPF: the authorised sending servers are listed in DNS.
• DKIM: outbound messages are signed and the signature validates.
• DMARC: the domain has a clear policy for failed authentication.
• Sender identity: the visible name, sending domain, signature, and reason for contact fit together.
• Sending rhythm: a quiet domain does not suddenly become a high-volume broadcaster.
• Message construction: a short, specific business note is safer than a generic promotion full of links, images, and claims.

SPF, DKIM, and DMARC are not a shortcut through a filter. They are the technical basis that lets a receiving provider verify who is sending. A separate outreach domain and a gradual ramp-up also help protect the company’s primary domain; see A Separate Domain for Cold Email: Protecting Your Primary Domain.

Daily bounce-review protocol

Do not investigate bounces one by one from an inbox. Once per business day, export or record campaign statuses and group them by reason, recipient provider, recipient domain, and sender domain. This is enough to distinguish a bad list from an infrastructure issue.

1. Separate explicit hard bounces: missing mailboxes, invalid domains, and disabled addresses.
2. Suppress them from the current and all future sequences, retaining the reason.
3. Put soft bounces in quarantine rather than an endless retry loop.
4. Group temporary and policy-related refusals across Yandex 360, Mail.ru, and other recipient domains.
5. Pause new sends from the affected mailbox or domain when the same pattern repeats.
6. Review authentication, sending pace, message content, and recent campaign changes.
7. Resume gradually only after the cause is addressed, beginning with a small control segment.

Maintain one suppression list for hard bounces, explicit opt-outs, removal requests, and complaints. It is not just database hygiene: it prevents an excluded contact from re-entering a future email, LinkedIn, or Telegram sequence. Telegram frequently plays the relationship and follow-up role that LinkedIn plays in many Western markets, but it is not a reason to bypass a clear request not to be contacted.

FAQ

Should every 5xx response be removed immediately?

Remove addresses when the text confirms that the mailbox, user, or domain does not exist, or the mailbox is permanently disabled. A 5xx response mentioning policy or reputation needs sender-side investigation before you classify the contact as invalid.

How many times should we retry a soft bounce?

Use a limited, spaced retry rule and then quarantine the contact after repeated equivalent failures. Avoid rapid retries; the provider has already indicated that it cannot or will not accept the message at that time.

Does no reply mean the email bounced or went to Spam?

No. No reply is an outcome, not a delivery diagnosis. Check delivery status separately, then assess targeting, offer, sequence, and inbox placement.

Why do Yandex 360 and Mail.ru need separate monitoring?

They are important recipient ecosystems for Russian business email and may return patterns that are easy to miss in an aggregate deliverability dashboard. Grouping their responses makes a provider-specific issue visible sooner.

Can we move a bounced contact to Telegram or LinkedIn?

Only if the bounce does not represent an explicit opt-out or removal request, and the new contact is relevant and appropriate. A channel change should improve relevance, not evade a recipient’s decision.

If you are preparing a Russia or CIS campaign, send OT9 a sequence or target list for a low-pressure teardown. We can review the delivery logic, list risks, and channel mix through our email outreach service or via the contact form.