The provider says the account works. What do I check on my side?

Three things: the port and TLS combination, the From address, and whether your network or application is rewriting the sender. Then read the exact error the server returned. If the error is a 535 the login is failing even if the password is right, and the username format is the usual cause.

Should a new account be warmed up?

Yes, unless the provider has warmed the IP and tells you so. Even then, a new domain needs its own ramp. Start with small volume to recipients who are likely to engage, and increase gradually rather than opening with a full list.

Can I send from the account using a different domain?

Only if the provider allows it and you have published SPF and DKIM for that other domain. Many providers restrict the sender to domains they have verified. Attempting to send off-domain produces a relay error, which looks like a suspension but is a scope rule.

You Bought an SMTP Account and It Will Not Send

The short answer

Work down the layers: does the login authenticate, does the connection use a port your network allows, does the From address match the domain you authenticated, and do SPF and DKIM pass. Most new accounts that will not send fail at the sender address or the port, not at reputation.

A new account that fails immediately is almost never a reputation problem: reputation takes a history to acquire. It is a configuration problem, and the layers are testable in order. Doing that saves a support ticket that begins with "not working" and ends three days later at a mistyped username.

Authenticate before anything else

Log in with the exact host, port and credentials you were given, from a mail client rather than your sending application. If the client cannot authenticate, nothing downstream matters. Copy the password rather than typing it, and check whether the username is a full email address or a bare name, because that differs between providers.

If authentication fails, check whether the account is enabled, whether it is restricted to certain IPs, and whether it needs an app-specific password rather than the webmail password. Those three account for most first-day failures.

Then the port, then the sender

A connection that hangs on port 25 is your network, not the provider. Submission ports 587 and 465 are what a client should use, and 587 with STARTTLS or 465 with implicit TLS are the two standard combinations. Mixing them, 465 without TLS for example, produces a connection that opens and then fails.

Next, the From address. A bought account is usually tied to a domain, and sending as an unrelated address, including a free mail address, is rejected by the provider or fails authentication at the receiver. Send as the domain the account belongs to, and publish SPF and DKIM for that domain.

Port 587 with STARTTLS, or 465 with implicit TLS; not 25 from a home or cloud network.
Username as given, often the full address, and a password that has not been truncated.
From address on the authenticated domain, with a matching reply-to if you need one.
SPF includes the provider, DKIM selector published, DMARC present.
One test message to a mailbox you control, then read the header.

Only then consider reputation

If authentication and sending both work and the mail lands in spam, you are now in the reputation conversation, which is a different page. A brand-new domain or IP has no history, and the first days should be small volume to real recipients rather than a campaign.

The useful distinction is between a send that fails and a send that is filtered. A failure produces an error code from the server you connected to. A filtered message produces a success and then arrives in the wrong folder. Only the first is a setup problem.

Worked example: a reseller who sold a working account

A reseller delivered an SMTP account to a customer who reported it as broken within an hour. The reseller tested it and it worked. The customer was setting the From address to their own Gmail account while authenticating as the reseller's domain, and the provider rejected it with a relay error that the customer had read as "account suspended".

The account had never been faulty. The customer then moved to sending as their own domain, published SPF and DKIM, and started at 50 messages a day. Delivery was unremarkable from the first day, which is what a correctly configured account looks like.

The support cost came entirely from the gap between an error code and its interpretation. A short checklist delivered with the credentials would have removed it, and that is now what the reseller sends with every account.

Symptom, layer, and the fix

Symptoms	Layer	What to change
535 authentication failed	Login	Recheck username form and password, enable the account
Connection timed out	Port or network	Use 587 or 465, not 25
550 sender rejected	From address	Send as the authenticated domain
Accepted but in spam	Authentication or reputation	Check SPF and DKIM, then warm up slowly
550 relay not permitted	Authorisation scope	Confirm the account may send off-domain or stop trying to

An error code tells you which layer refused. The wording varies between providers, so read the code before the sentence.

Triage in this order

1Authenticate with a mail client, not your campaign application.
2Confirm the host, port and TLS mode match what the provider documented.
3Send as the domain the account belongs to.
4Publish SPF and DKIM for that domain and verify with a test message.
5Send one message to a mailbox you control and read the received header.

Where this connects on this site

If you are choosing where to buy, see accounts tested before delivery
To test an account end to end, use the SMTP tester
If the error code does not match anything here, contact support

What this will not do

An account that authenticates does not guarantee delivery; receivers decide per message.
A new account has no reputation, and no provider can supply one at purchase.
Sending as a domain you do not control will be rejected, and trying repeatedly can suspend the account.
This page covers setup failures, not deliverability to a specific mailbox provider.

Questions this page gets asked

The provider says the account works. What do I check on my side?: Three things: the port and TLS combination, the From address, and whether your network or application is rewriting the sender. Then read the exact error the server returned. If the error is a 535 the login is failing even if the password is right, and the username format is the usual cause.
Should a new account be warmed up?: Yes, unless the provider has warmed the IP and tells you so. Even then, a new domain needs its own ramp. Start with small volume to recipients who are likely to engage, and increase gradually rather than opening with a full list.
Can I send from the account using a different domain?: Only if the provider allows it and you have published SPF and DKIM for that other domain. Many providers restrict the sender to domains they have verified. Attempting to send off-domain produces a relay error, which looks like a suspension but is a scope rule.

Last reviewed 2026-10-27. Written for readers in the United States and elsewhere; rules about access, email and consent differ by country, and nothing on this page is legal advice.