Why Can't I Send Email from TrekMail?

Outbound failures have a small set of common causes. Work through these checks in order. If the account and domain are ready but only one recipient rejects a message, the recipient's mail server may be the next place to investigate.

Check 1: Account-owner email is not verified

If you registered a new TrekMail account on or after 19 February 2026 and haven't clicked the email-verification link, sending is blocked after a 7-day grace period. The dashboard shows a red banner: "Sending blocked, please verify your email."

This applies to the account owner's sign-in email, not your mailboxes. If the owner email is unverified, every mailbox on the account stops sending until verification clears.

Fix:

• Look in the inbox of your sign-in email for the verification email TrekMail sent at registration, then open its link.
• Lost the email? Click the Resend verification email link in the banner.
• If you use a social sign-in method, check the account's verification state in the Dashboard instead of assuming the provider verified it.
• If a link no longer works, request a new email rather than reusing an old link.

Accounts registered before 19 February 2026 are grandfathered and not subject to this block.

Check 2: Domain DNS is not verified

TrekMail requires the domain to be ready before it can use the managed sending route. The DNS page shows the specific record that is still missing, conflicting, or being checked. SPF, DKIM, and DMARC also help receiving providers assess the mail you send.

Symptom: "Domain not verified" status on the Domains page; mail leaves but bounces back; recipients report mail in spam.

Fix: Open the Domains page, select the domain, and open its DNS status. Compare each record with the values shown there, save corrections at your DNS provider, then use Verify DNS to request another check. The result may remain pending while public DNS updates. Walk-through: Checking DNS Status.

Check 3: You are on Nano

The Nano plan has can_send: false at the plan level. Authentication to SMTP completes, but every send is rejected at the submission stage.

Symptom: Client says "Sending failed" with a 5xx error; mail goes to outbox briefly then comes back.

Fix: Choose a plan with managed sending in the Plans page, then check the active plan and domain status before retrying.

If you must stay on Nano, configure BYO SMTP for the domain. Custom SMTP is available on all plans, including Nano. You provide credentials for an external SMTP provider, and TrekMail uses that selected route for the domain. Receiving through IMAP continues independently of the outgoing route.

Check 4: Daily or hourly sending limit reached

Each plan has maximum daily limits per mailbox and account, an hourly rate cap, and a per-message recipient cap:

(Nano can authenticate, but its managed sending route is off. Current limits can be lower for a new domain, an account without prior paid history, or a trial. Treat this table as the plan maximum and use the Dashboard for the current allowance.)

Symptom: Sends work fine, then partway through the day every new send fails with "user has exceeded sending quota" or a similar 4xx error.

Fix: Stop retrying a large batch and wait for the relevant allowance to become available. The hourly limit is a short rate window and the daily quota is counted by day. If you need more ongoing capacity, review the plan and its sending policy before upgrading; an upgrade does not erase messages already rejected.

Check 5: Recipient count per message

Beyond the daily limits, each message has a per-message recipient cap: 50 Nano, 100 Starter, 250 Pro, and 500 Agency. A message above the cap can be rejected before it is sent.

Fix: Split into batches that fit, or upgrade.

Check 6: The mailbox cannot send

The mailbox must be active and allowed to send. A mailbox can be disabled, its sending ability can be unavailable after a plan or domain change, or its outgoing mail can be temporarily paused for a safety review. These are different states, so read the message in the Dashboard or mail app before changing settings.

Symptom: sending fails for one mailbox while another mailbox on the same account can send.

Fix: Open the mailbox in the Dashboard and confirm that it is active. If the message identifies an account, plan, or domain issue, resolve that first. Do not assume a sign-in suspension is the cause: sign-in suspension normally blocks login but does not itself stop incoming mail.

A temporary sending pause

A mailbox can have only its sending stopped while incoming delivery and reading continue. This can happen when activity suggests that the mailbox credentials may have been exposed. It protects the domain while the account owner reviews access.

Symptom: mail still arrives and you can still read it, but outgoing messages do not leave the mailbox:

• In webmail: "Sending from this mailbox is paused after unusual activity. Please contact support to resume it."
• In a mail app: sending fails while receiving keeps working, and the app reports that the server would not accept your address as the sender.
• Through the API: the send is refused with the error code mailbox_sending_paused.

Fix: this requires a support review. The ordinary mailbox status controls do not lift a sending-safety pause.

1. Change the mailbox password (see Mailbox Security).
2. Update the new password anywhere the mailbox is set up: phone, mail app, script, or tool that sends through it.
3. Open a ticket from the Support page and say that you changed it. Include the mailbox address and the approximate time, but never include the password.

Mail can still arrive while this review is in place. Save important draft text locally until sending is restored.

Check 7: Account is suspended

An account-level suspension can block outgoing mail and other account actions. The Dashboard shows a banner explaining the reason, such as:

• "There is a billing issue with your account. Please update payment details or contact support." Billing issue: update payment details, then check the account's billing state. See Fixing Failed Payments.
• "We've temporarily paused outbound mail because too many of your recent messages were rejected by recipient servers." Deliverability issue: open a support ticket. The team may ask about list hygiene, sender setup, and a redacted message sample before it can be reviewed.
• "Your account is temporarily restricted. Please contact support for details." Abuse or security issue: open a support ticket for review.

You can't sidestep an account-level suspension by switching mailboxes or domains. The block applies to everything outbound on the account until lifted.

Check 8: SMTP authentication itself fails

If your client says "535 Authentication failed" or "Invalid credentials":

• Wrong password. Most common cause is mixing up the account-owner password with the mailbox password. SMTP wants the mailbox password.
• Mailbox does not exist. Check the Mailboxes list. A setup typo can mean the mailbox is different from the one configured in the app.
• Account-owner email unverified past grace. See Check 1. Verification is enforced at submission.

If you reset the mailbox password recently, update the saved password in every mail app, then reconnect and retry. Do not keep retrying an old password because it can create a separate lockout or connection problem.

Check 9: BYO SMTP misconfiguration

If a domain is using a custom external SMTP provider:

• Verify the external provider's credentials on that domain's SMTP tab: Domains, choose the domain, then SMTP.
• Confirm you've enabled SMTP submission with that provider (some providers require domain verification on their side too).
• Use the test action on the domain's SMTP tab and read the result before sending live mail.

If the external credentials are invalid, sending can fail with a general error. Correct them at the provider, save the connection, and run the test again.

Check 10: The recipient's server is rejecting you

If everything on TrekMail's side is green but specific recipient domains bounce:

• The recipient's server may have an issue with your sender reputation (new domain, no warmup, SPF/DKIM not aligned). See Bounce Rate Too High and Domain Warmup Rules.
• If many unrelated recipient domains start failing at the same time, check the TrekMail status page and include the error and timestamps in a support ticket.
• Some receivers reject mail when sender authentication is incomplete or the domain has a weak DMARC policy. Review SPF, DKIM, and DMARC before changing content or retrying a batch.

Common error codes decoded

Still stuck

Open a ticket from the Support page. Include:

• The sending mailbox (alice@yourcompany.com).
• The recipient's address (or a sample one, if many bouncing).
• The exact error from your client or the bounce message.
• Whether webmail can send the same message to the same recipient. (If webmail also fails, the issue is server-side.)

For a deliverability-suspension review, be ready to explain how recipients opted in and provide a redacted sample if support asks. Do not send a full mailing list, credentials, or unrelated recipient data in the ticket.