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: the Dashboard shows the daily account allowance that actually applies today, and each domain's SMTP tab shows that domain's limits for today, including a new domain's warm-up and the dates they rise.)

Symptom: Sending works, then partway through the day new messages stop going out and you see one of these:

• In webmail, a window opens over your message, which stays open. It shows how much of the limit has been used, why the limit is lower right now (a trial or a new domain), and when it renews, in your own time zone.
• In a mail app, sending fails with a temporary reply that contains the code 4.7.1, the limit that was reached, the numbers, and the renewal time, for example "Daily sending limit reached for this account (50 of 50 today; trial account). Sending resumes at 00:00 UTC." or "Hourly sending limit reached for this account (15 per hour; trial account). Sending resumes at 14:00 UTC."

Fix: Read the message first: it says which limit was reached and when it renews. Then:

• Wait for the renewal instead of retrying. Daily limits renew at 00:00 UTC, and the hourly limit at the top of each hour (UTC).
• On a trial, whoever manages billing can end the trial early from Billing → End trial and start subscription now. The paid subscription starts and the trial limits are lifted at once.
• A new domain warms up over its first 7 days (40% on days 1 to 3, 70% on days 4 to 7, the full limit from day 8). This lowers only that domain and its mailboxes; your other domains keep their full allowance.
• Forwarded mail counts too. Forwarded messages that leave TrekMail use the same daily account allowance as the mail you send.
• Upgrading raises the plan's allowance. During a trial it does not lift the trial limits (ending the trial does), and it never resends messages that were already refused: send those again once there is room.

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. On a trial, the cap is 10 recipients per message until the first payment; webmail warns you before sending a message over the cap and will not schedule one.

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. Reconnect each phone, mail app, or SMTP script with a new app password, or the new mailbox password if the mailbox still accepts it. An admin password reset revokes all app passwords; in webmail, select Also revoke all app passwords when changing your own password after a compromise.
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 or sign-in mode. SMTP needs an app password for a mailbox in App passwords only. In Mailbox password or app passwords, either works. Never use the account-owner dashboard password. Create an app password in webmail under Settings > App passwords, or in the dashboard under Mailboxes > (mailbox) > Security > App passwords.
• 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 the app says "Sign-in failed. This mailbox accepts app passwords only: create one in webmail under Settings > App passwords.", create an app password and enter it for both incoming and outgoing mail. Some apps show only "password incorrect". See Mail app passwords.

An admin password reset or password recovery revokes all app passwords. Create new ones for affected apps, or update the mailbox password where it is still accepted, then reconnect. Do not keep retrying a revoked or old password.

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.