550 — Message rejected under suspicion of spam (Mail.ru)
Retrying will not help. The message will not be delivered.
The reply
550 Spam message rejected / 550 Message rejected under suspicion of SPAM.Mail.ru's filter refused the message outright. Unlike most receivers it gives you somewhere concrete to look: the postmaster office shows your reputation and complaint rate per domain, and the answer is usually visible there.
What it means
A permanent rejection on content and reputation together. Mail.ru weighs the sending domain's reputation, the complaint rate from its own users, authentication and the message itself. The important practical point is that the recipient sees nothing at all — this is a refusal at SMTP time, not a spam-folder placement.
Why it happens
- Complaint rate above what Mail.ru tolerates — visible in the postmaster office.
- A domain with no reputation at Mail.ru, sending at volume for the first time.
- Missing or unaligned SPF, DKIM or DMARC.
- Content resembling bulk advertising: one image, heavy promotional wording, a shortened link.
- Mail to addresses that did not subscribe, including an imported list.
What to do
- Register the domain at postmaster.mail.ru. Reputation, complaints and delivery are all shown there, free, per domain.
- Fix SPF, DKIM and DMARC alignment before anything else — Mail.ru weighs authentication heavily.
- Add List-Unsubscribe with one-click so people opt out instead of complaining.
- Reduce volume and rebuild gradually if the domain is new to Mail.ru.
- Remove recipients who never open, and everyone who has ever complained.
Questions
Is it in the spam folder?
No. The message was refused during the SMTP session, so it was never accepted and is in no folder at all.
What does the postmaster office give me?
Per-domain reputation, complaint rate, delivery and spam statistics for mail you send to Mail.ru Group domains. It is the only direct view of how they see you, and it needs a DNS record to confirm the domain is yours.