Is This SMTP Account Actually Ready to Send?

Checks one to three: authentication and basic send

Send a message to an address you own at a major consumer provider, then open the full headers. That single message proves more than any control panel: it shows whether the connection was encrypted, which server accepted the message, and whether authentication passed. Keep the headers.

Then check the protocol: a submission port with STARTTLS is the normal outbound path, and the account should refuse to send at all if encryption is not offered rather than quietly sending in clear text. An account that permits unencrypted authentication is a liability, because your password leaves the machine in the open.

• The credentials authenticate over an encrypted connection, not plain text.
• A message to your own address arrives, and the headers show the correct sending server.

Checks four to six: the domain has to vouch for the server

SPF is a DNS record on the sending domain listing the servers allowed to send for it. If the record does not include the server you are using, receivers treat your message as unverified. The check is a DNS lookup of the domain's TXT records; the test is a message to a mailbox that reports authentication results in its headers.

DKIM is a cryptographic signature added by the sending server. It needs a selector published in DNS by the domain owner and signing enabled on the server. The test is the same message headers: a passing DKIM result names the signing domain and selector, so you can confirm both the signature and the alignment.

DMARC is the policy that tells receivers what to do when SPF and DKIM do not align with the visible From address. It is the record that decides whether a misconfigured server gets your mail rejected or merely flagged, and it is also the record that tells you who is sending as your domain.

Checks seven to nine: reputation and identity of the address itself

Forward DNS resolves the server name to an address; reverse DNS resolves the address back to a name. A matching pair is what receivers expect from a legitimate sending host. A mismatch is not fatal, but it is one more reason for a filter to be cautious.

Warm-up is the part people skip. A fresh address has no sending history, so a sudden few hundred messages is anomalous regardless of how good the copy is. The first days should be a small, engaged, low-complaint volume: your own team, people who replied to something, a small segment of a clean list.

Checks ten: bounce and complaint handling exist before you need them

Every campaign needs an address to receive bounces and a policy for what happens next. Hard bounces should be removed permanently, complaints should be suppressed immediately, and soft bounces should be retried a limited number of times. If those rules live in someone's head, the list will be dirty within a month.

The practical test is to send to an address you know does not exist, then watch whether the bounce comes back to the account rather than disappearing. A sender that swallows bounces cannot clean a list, and a list that never gets cleaned is the usual reason an account gets restricted later.

Worked example: a mailbox that passed the login and failed the inbox

A recruiter buys a mailbox, logs in successfully, personalises a first batch of sixty messages and sends them. The dashboard says sixty sent. By the next morning four replies had arrived, all of them confused, and none from the people he actually wanted. The rest had gone to spam or been silently discarded.

The headers showed why: SPF passed for the provider's own domain, but the visible From address was his company domain, which published no SPF record and no DMARC record at all. The provider was authorised to send for itself, not for him. DKIM was signing with the provider's selector, so it also failed to align.

The fix took an afternoon and no new purchase: an SPF record including the provider, DKIM enabled with his own selector, a DMARC record in reporting mode, and a restart at fifteen messages a day to people who had replied to him before. The mailbox had been technically ready and commercially useless for a week because three DNS records were missing.

The ten checks, what each proves, and how to settle it

A bought mailbox should arrive checked against every line above. LocalSMTP accounts are tested live before delivery rather than described as ready.

The order to do these in

• 1Authenticate and send one message to an address you own. Save the full headers.
• 2Read the authentication results in those headers before changing anything else.
• 3Look up the SPF and DMARC records yourself with a DNS query, so you are not trusting a dashboard.
• 4Confirm DKIM signing is on and the selector resolves.
• 5Check forward and reverse DNS for the sending address.
• 6Ask the provider what the address was used for before you got it.
• 7Start warm-up at a small volume to engaged recipients, and log it.
• 8Write down the bounce and complaint rules in one page, and who applies them.
• 9Only then plan a campaign that matches the volume the warm-up has earned.