Mailbox provider · Sina Mail
How to verify a sina.com email address
Sina Mail addresses can be verified without sending an email. On 13 October 2026 the sina.com mail server freemx1.sinamail.sina.com.cn rejected a made-up recipient at the SMTP RCPT TO step with 554 User no found., so a mailbox check can tell a missing sina.com account from a real one.
Mailbox checks: Verifiable. The server rejects unknown recipients during the SMTP conversation.
Sina Mail at a glance
| MX hosts | freemx1.sinamail.sina.com.cn, freemx2.sinamail.sina.com.cn, freemx3.sinamail.sina.com.cnObserved 13 October 2026 (dig MX) |
|---|---|
| Answer to a made-up address | 554 User no found., returned at RCPT TOObserved 13 October 2026 (SMTP probe of a made-up recipient, no message sent) |
What Sina Mail's server says about a missing mailbox
The reply that matters is the one to RCPT TO, the step where the checking server names the recipient. Sina Mail answered our made-up sina.com address with 554 User no found.. A 5xx code at that step is a permanent "no such mailbox", which is the same answer a real message would get, so SimpleVerifier marks the address invalid with the reason "Mailbox not found". A 250 at the same step means the mailbox exists and comes back valid.
Before trusting a "valid", a careful verifier also offers a random address that cannot exist. Sina Mail rejected ours, so sina.com is not a catch-all: a 250 for your address is a real signal. Temporary 4xx replies (421, 450, 451) are about the connection, not the mailbox, and come back risky with "Server would not confirm" rather than invalid. Hard bounce vs soft bounce explains why that split matters.
Sina answers with 554 and the text "User no found." at RCPT TO: a permanent rejection of that mailbox, unusual wording aside.
Cleaning sina.com addresses on a list
Because Sina Mail answers honestly, sina.com is one of the domains where verification removes bounces before they happen. Drop the invalid results, keep the valid ones, and re-check the risky ones later: a temporary reply on one day often turns into a clear answer the next.
A valid result only means the mailbox exists today. Addresses on an old consumer list go stale as people stop using them, so re-verify before each large send to an aged segment; how often to verify an email list gives a schedule. Upload the CSV to the verifier and download the valid, risky and invalid rows as separate files.
Live DNS check for sina.com
These are sina.com's own sending records, refreshed daily. They describe mail sent from the domain, not whether a given address at it exists.
3 of 5 checks passed
60%Blocklist status
Not listed on SURBL, SpamCop
DKIM — message signing
No DKIM found on common selectors — it may use a custom one
DMARC — spoofing policy
DMARC present but p=none, so nothing is enforced
Mail servers (MX)
3 mail server(s), primary freemx2.sinamail.sina.com.cn
SPF — authorised senders
SPF present, strict (-all)
Common questions
- Can I check if a sina.com address exists without emailing it?
- Yes. A verifier connects to Sina Mail's mail server, names the address at the RCPT TO step and disconnects before sending. On 13 October 2026 the server rejected a made-up sina.com address with "554 User no found.", so a missing mailbox shows up as invalid and the owner receives nothing.
- What mail servers does sina.com use?
- On 13 October 2026, sina.com published these MX hosts: freemx1.sinamail.sina.com.cn, freemx2.sinamail.sina.com.cn, freemx3.sinamail.sina.com.cn. You can look them up yourself with the free MX lookup tool.
- Why did a sina.com address come back risky instead of invalid?
- Risky means the server didn't give a permanent answer during the check, usually a temporary 4xx reply or a timeout. It isn't proof the address is bad. Check it again later; Sina Mail gave a clear rejection for a missing mailbox when we tested it.
Check a Sina Mail address
The free checker runs the mailbox check on one address and shows the server's reason, so you can see which of the cases above applies.