Mail.ru Email Deliverability: What You Need to Know
Mail.ru (including bk.ru, list.ru, inbox.ru, and mail.ua) is Russia's largest email provider. These domains account for 40% to 60% of addresses in a typical Russian-language list. If your messages aren't reaching Mail.ru, you're losing half your audience.
Mail.ru filters email differently from Gmail. Different priorities, different signals, different thresholds. Gmail advice only partially applies here. Below is exactly where the differences lie and what to do about them.
How Mail.ru filtering works
Mail.ru runs Kaspersky Anti-Spam (KAS) alongside internal algorithms. Filtering is layered: IP and domain first, then authentication (SPF, DKIM, DMARC), then message content, then recipient behavior.
The main difference from Gmail: Mail.ru relies far more heavily on the sending IP's reputation. Gmail shifted focus to domain reputation years ago; at Mail.ru the IP still matters. A fresh dedicated IP or one that has appeared on local blocklists causes delays or spam placement even when the domain is clean.
Mail.ru also uses greylisting aggressively. On the first connection from an unknown IP, the server returns a 4xx temporary rejection. Legitimate mail servers retry after a few minutes; spam scripts usually don't. If your ESP mishandles 4xx responses, a portion of messages will never arrive, and the logs will show soft bounces rather than a sender-side problem.
Karma: Mail.ru's internal reputation score
Mail.ru builds an internal score called Karma from dozens of signals. It determines placement: inbox, the "Newsletters" folder (similar to Gmail's Promotions tab), or spam.
What affects Karma:
- Spam complaints — the primary negative signal. Even a 0.2% complaint rate visibly hurts Karma.
- Bounce rate — Mail.ru watches hard bounces closely. Sending to nonexistent @mail.ru addresses is a direct hit to reputation.
- Spam traps — Mail.ru maintains both recycled traps (abandoned addresses put into monitoring) and pristine traps (never-used addresses).
- Engagement — opens, clicks, and moving messages from spam to inbox all push Karma up.
- Volume consistency — sudden spikes raise flags; a steady stream with gradual growth does not.
Karma isn't a public number, but its effects show up in Postmaster Mail.ru. As Karma drops, messages move from "Newsletters" to spam, and at very low scores the server begins rejecting connections.
Postmaster Mail.ru: what to watch
Postmaster Mail.ru (postmaster.mail.ru) is a free monitoring tool for bulk senders. Add your domain, verify via DNS record, and data accumulates within 24 to 48 hours.
Domain and IP reputation
Separate charts for the domain and each IP, so you can pinpoint whether a problem is domain-level or tied to one specific IP.
Delivery by folder
Percentage of messages in inbox, "Newsletters," and spam. This folder-level breakdown doesn't exist in Google Postmaster Tools.
Authentication errors
SPF, DKIM, and DMARC pass/fail counts per campaign. Misconfiguration shows up as concrete numbers.
Complaints and unsubscribes
Complaint rate over time. A spike is a prompt to identify which campaign caused it.
Check Postmaster Mail.ru at least once a week. Gmail and Mail.ru can react differently to the same campaign. It happens that Gmail looks clean while 15% of Mail.ru messages land in spam. Two providers, two separate monitoring tasks.
Authentication: where Mail.ru is stricter
SPF, DKIM, and DMARC are all required. But there are specifics that catch even experienced senders.
SPF and the DNS lookup limit. Mail.ru enforces the 10-lookup cap strictly. Gmail sometimes overlooks an 11th lookup; Mail.ru does not. An SPF record with too many include mechanisms returns PermError. If you use multiple ESPs, flatten your SPF record.
DKIM key length. Mail.ru accepts 1024-bit and 2048-bit keys. If you're still on 1024, upgrade now. Providers are moving toward 2048 as the practical minimum.
DMARC alignment. Make sure DKIM is signed with your domain, not your ESP's domain. Otherwise DMARC fails, and with a policy of p=quarantine or p=reject messages go to spam or get rejected entirely.
The "Newsletters" folder: not spam, but not the inbox either
In 2023 Mail.ru introduced a "Newsletters" folder similar to Gmail's Promotions tab. Marketing messages are sorted there automatically. Based on our data, open rates in "Newsletters" run 30 to 50% lower than for the same messages landing in the inbox.
Landing in "Newsletters" is expected for bulk mail. To reach the inbox consistently, you need to build engagement signals.
What helps move messages to the inbox:
High open rate. When 40%+ of recipients open consistently, Mail.ru gradually shifts delivery to the inbox.
Replies. A reply is the strongest engagement signal. If a user replies to a campaign, subsequent messages from that sender are very likely to land in the inbox.
Manual moves. When a user drags a message from "Newsletters" to the inbox, the algorithm learns that preference per recipient.
Adding to contacts. If the sender address is in the recipient's address book, messages go to the inbox. Ask engaged subscribers to add you.
Transactional messages (order confirmations, password resets, receipts) land in the inbox when sent from a subdomain and IP separate from your marketing stream. Mix the streams and transactional messages will suffer when marketing reputation dips.
IP warm-up for Mail.ru: slower than Gmail
Mail.ru is more conservative with new IPs than other providers. Where Gmail typically needs 2 to 3 weeks of warm-up, budget 3 to 5 weeks at Mail.ru. Greylisting adds delays in the first days and you need to scale more gradually.
A workable approach: start at 50 to 100 messages per day to @mail.ru and related domains. Increase by 50% every 2 to 3 days, but only if bounce rate stays below 2% and complaints are near zero. Send first to your most active subscribers: people who opened or clicked within the last 30 days.
Common mistake: warming up through Gmail only, then blasting the full Mail.ru segment at once. Mail.ru sees that as a first contact from an unknown IP. Gmail reputation doesn't carry over. Warm up across all major providers in parallel, splitting volume proportionally.
Content filtering: what triggers Mail.ru
Mail.ru's anti-spam engine analyzes text, HTML, links, and attachments. Several things cause problems more consistently than others:
URL shorteners. bit.ly, clck.ru, and similar services are a red flag. Use full URLs or a tracking subdomain on your own domain.
Image-only emails. Messages where all content is one or two images with no text get filtered more aggressively here than at Gmail. Keep text-to-image ratio at least 60/40.
JavaScript and forms in the body. Mail.ru strips JS and truncates HTML forms. Leftover script tags in your template are an extra negative signal.
Broken HTML. Unclosed tags, inline styles from Word, bloated CSS. Templates that render cleanly in Gmail can break in Mail.ru. Test rendering specifically here before sending.
Mail.ru vs Gmail vs Yandex: practical differences
Gmail evaluates domain reputation above all. IP reputation is secondary when sending through a major ESP. Push complaint rate above 0.3% and you're in spam with a slow road back.
Yandex uses its own filter and Postmaster. Behaviorally closer to Mail.ru than Gmail: IP reputation matters, greylisting is present. But Yandex is more lenient with new senders and recovers from mistakes faster.
Mail.ru is the most conservative of the three. Slowest to accept new IPs, strictest on authentication, most aggressive with greylisting. The upside: Postmaster Mail.ru offers per-folder delivery breakdowns that Google Postmaster Tools doesn't. Once reputation is solid, Mail.ru is reliable. Most problems happen at the start or after sharp changes in sending patterns.
Checklist: fixing Mail.ru deliverability
Everything covered above, in order from basic setup to more advanced steps.
Connect Postmaster Mail.ru and set up weekly monitoring. Without data, every other step is guesswork.
Audit SPF, DKIM, and DMARC. Confirm your SPF stays under 10 DNS lookups. Upgrade DKIM to 2048-bit.
Validate your list: remove invalid @mail.ru, @bk.ru, @list.ru, and @inbox.ru addresses. Each hard bounce hits Karma directly.
Split marketing and transactional traffic onto separate subdomains and IPs.
Confirm your ESP handles 4xx responses and retries. Without retries, greylisting will gut deliverability.
Warm up the IP for Mail.ru separately. Start at 50 to 100 messages per day and increase by 50% every 2 to 3 days.
Remove URL shorteners. Use your own subdomain for click tracking.
Test HTML rendering in Mail.ru before sending. What works in Gmail may break here.
Add the List-Unsubscribe header. Mail.ru surfaces an unsubscribe button in the UI, which reduces spam complaints.
Common mistakes with Mail.ru
Ignoring 4xx errors. "Soft bounce 12%" on Mail.ru looks like a provider problem. It's greylisting, and the ESP isn't retrying. Fix: switch ESP or configure retry manually.
One IP for everything. One bad marketing campaign tanks reputation, and order confirmations stop getting through too.
Sending to a stale, unvalidated list. Thirty percent of @mail.ru addresses dead, never cleaned. First send produces 15% bounce rate and the IP lands on Mail.ru's internal blocklist. Recovery takes weeks.
Warming up only through Gmail. Great Gmail reputation built up, Mail.ru never touched. Then the full @mail.ru segment goes out at once, and the result is mass rejection.
Summary
Mail.ru is not harder than Gmail. It is different. More attention to IP reputation, greylisting on incoming connections, a separate "Newsletters" folder, strict authentication checks. Account for these from the start and Mail.ru deliverability won't be a recurring problem.
The foundation is the same as for any provider: a clean list, correct authentication, a gradual warm-up, and monitoring. For Mail.ru specifically, add a separate Postmaster setup, a check of your ESP's retry logic, and a slower ramp.
Start with the list. If your @mail.ru segment contains dead addresses and spam traps, no amount of configuration will save you.
Validate your @mail.ru addresses with uChecker before sending. Remove invalid addresses and traps from your list.
Validate your list for free