I Can’t Send Emails

Outbound failures fall into one of about ten categories. Work through these in order — the first match is almost always the cause. If everything checks out and you still can't send, the issue is usually on the recipient side (their server rejecting your sender reputation), not yours.

Check 1 — Account-owner email isn't 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. Click the link. Verified accounts unlock sending instantly.
• Lost the email? Click the Resend verification email link in the banner.
• If you signed up with Google, your email is auto-verified — sending should work immediately.
• If you signed up with Facebook, X, or Microsoft and completed the 6-digit email-confirmation step, you're verified too.
• The verification email expires after a window (we re-issue on resend). Don't paste old links.

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

Check 2 — Domain DNS isn't verified

For each domain, TrekMail requires SPF and DKIM (DMARC is strongly recommended) to be configured correctly. While we don't block sending solely on missing DNS, recipient servers will reject or spam-fold your mail without these records.

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

Fix: Open the Domains page, click the domain, click Verify DNS. The status flips to Active once all required records resolve. Walk-through: Checking DNS Status.

Check 3 — You're 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: Upgrade to Starter or higher in the Plans page. Send capability turns on the moment the upgrade subscription activates.

Workaround if you must stay on Nano: configure BYO SMTP in your account settings. Custom SMTP is allowed on all plans, including Nano — you provide credentials for an external SMTP provider (Mailgun, SendGrid, your hosted server) and TrekMail relays mail through it. Receiving via IMAP still works as normal.

Check 4 — Daily or hourly sending limit hit

Each plan has a daily send limit per mailbox and per account, plus an hourly rate cap:

(Nano can authenticate but can_send is false; the daily limit shown applies to BYO-SMTP users.)

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: Wait — the counters reset rolling. The hourly cap clears within an hour; the daily cap clears at midnight UTC. For a one-off urgent batch, upgrade your plan; the new caps apply immediately on activation, no daily-counter reset.

Check 5 — Recipient count per message

Beyond the daily limits, each message has a per-message recipient cap (50 Nano / 100 Starter / 250 Pro / 500 Agency). Trying to send to 200 addresses on Starter rejects the whole message — not just the surplus.

Fix: Split into batches that fit, or upgrade.

Check 6 — Mailbox is paused

If an admin paused this specific mailbox (manually or via abuse-flag automation), all SMTP submission from it fails with authentication errors.

Symptom: Authentication fails consistently for this mailbox but other mailboxes on the same account work fine. The Mailbox detail page in the dashboard shows a Paused badge.

Fix: As account owner, open the mailbox detail page and click Resume. If the pause was admin-imposed (abuse flag), contact support before resuming — there's usually a reason.

Check 7 — Account is suspended

Whole-account suspension takes everyone offline. The dashboard shows a red banner at the top with one of these messages:

• "There is a billing issue with your account. Please update payment details or contact support." — billing suspension. Fix payment and the suspension lifts automatically. See Fixing Failed Payments.
• "We've temporarily paused outbound mail because too many of your recent messages were rejected by recipient servers. This is usually a quick fix — please reach out to support and we'll help you get sending again." — deliverability suspension. Open a support ticket; we work with you on list hygiene, content review, or sender setup before lifting.
• "Your account is temporarily restricted. Please contact support for details." — abuse or security suspension. 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 doesn't exist. Check the Mailboxes list — sometimes a typo in setup means the mailbox you think exists actually doesn't.
• Account-owner email unverified past grace. Same as Check 1 — verification is enforced at submission.

If you reset the mailbox password recently, the IMAP/SMTP servers pick it up within ~1 minute. Restart your client or wait briefly and retry.

Check 9 — BYO SMTP misconfiguration (if you set it up)

If you're using a custom external SMTP provider:

• Verify the external provider's credentials in SMTP Settings in your dashboard.
• Confirm you've enabled SMTP submission with that provider (some providers require domain verification on their side too).
• Run a test from the SMTP Settings page — we send a probe message and report success/failure inline.

External SMTP credentials are stored encrypted at rest. If they're invalid, every send fails with a generic 5xx — fix the credentials and retry.

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.
• Some receivers temporarily block all of TrekMail's outbound IPs during reputation events. We monitor and resolve these on our end; check the TrekMail status page if many recipients are bouncing at once.
• Some receivers reject mail with weak DMARC (none/quarantine→none). Add or strengthen your DMARC record.

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 deliverability-suspension issues specifically, plan to share the content of your recent sends and your list-acquisition process — we look for patterns that suggest list-hygiene problems before un-suspending.