Verifying Mail.ru addresses

• Unknown recipients usually return a 550, but the service also returns temporary failures under load without any clear pattern.
• Probes from IP ranges outside Russia and neighboring countries are refused more often, which is a geography problem rather than a policy one.
• The four main domains behave identically because they are the same platform wearing different names.
• Latency is high enough that timeouts, rather than rejections, become a meaningful share of results on a large batch.

• Cyrillic subject lines and sender names need correct encoding or they arrive as mojibake, which reads as spam to both the filter and the reader.
• Mail.ru's filtering is opaque and offers no postmaster tooling comparable to Google's or Microsoft's.
• Check your own compliance position before sending commercially into this market. That is a legal question rather than a deliverability one.

Say your deduplication pass treats mail.ru, inbox.ru, bk.ru and list.ru as one provider and merges rows that share a local part. Grouping them as one provider is right: a lookup on September 19, 2026 showed all four, plus internet.ru, on a single host, mxs.mail.ru. Merging them by local part is wrong. At signup a person picks one of those domains from a menu, and the same name on a different domain is a separate account that anyone else can register.

That's the opposite of Gmail and googlemail.com, where two domains mean one inbox. With 600 rows across the Mail.ru family, a merge by local part could silently fold dozens of different people together. Each surviving row then inherits the wrong name and consent record. Dedupe these on the full address only, and keep the provider grouping for pacing and reports.

The company behind Mail.ru renamed itself VK in 2021, and its business mail product hosts customer domains. Those tenants are told to publish emx.mail.ru as their MX, so a corporate-looking address can sit on this platform without the brand appearing anywhere in it. Check the MX before you decide how a domain will behave, and before you promise anyone a turnaround time on a Russian-language list.

Time is the practical cost on this platform. When a server throttles and answers slowly, a batch doesn't fail, it just runs long, and the rows still waiting at the end need a label. Ask how your verifier labels them, because a timeout is not a rejection. We return those rows as unknown with the reason attached, and they aren't billed. You can submit them again on another day without paying twice for the ones that resolved.