I Can’t Connect My Email Client

You've added the account in Outlook, Apple Mail, Thunderbird, or your phone — and it won't authenticate, won't sync, or just hangs. This article walks through the diagnostic path from the most common (typo in settings) to the more obscure (ISP port blocking, IMAP connection limit). Most issues resolve in the first three checks.

The settings you need

For any IMAP/SMTP client, the values are the same regardless of your domain:

Find these any time on the Connection tab inside your domain — there's a "Show settings" panel that copies each value to clipboard. If your client offers an autodiscover/autoconfig option, see Setting Up Apple Mail or Setting Up Outlook — those routes pre-fill everything.

Check 1 — Username is the full email address

The most common single error: typing just alice as the username instead of alice@yourcompany.com. TrekMail's IMAP and SMTP services authenticate by full email address, not by local-part. Username must include @yourdomain.com.

If your client has separate fields for "username" and "email address", both go to the same value — the full email.

Check 2 — Password is the mailbox password, not your dashboard password

When you logged in to TrekMail's dashboard, that was the account-owner password (the one tied to your sign-in email). When you created a mailbox, you set a mailbox password for that specific mailbox. These are two different secrets.

Email clients need the mailbox password, not the account-owner password. If you forgot it, you can either:

• Reset the mailbox password as the account owner from the Mailbox detail page in the dashboard.
• Have the mailbox user reset it themselves at the self-service password page.

If you've ever pasted your account-owner password into Outlook by mistake, you'll get "authentication failed" with no further details — the password is wrong from the IMAP server's perspective.

Check 3 — Hostnames are TrekMail's, not your domain's

Don't enter imap.yourcompany.com or smtp.yourcompany.com — those hostnames don't exist. The mailservers are:

• IMAP: imap.trekmail.net
• SMTP: smtp.trekmail.net

The domain in your email address (@yourcompany.com) only affects the username. The servers you connect to are always TrekMail's, regardless of which domain the mailbox lives on.

Check 4 — The right port + the right SSL/TLS mode

Pick 993 for IMAP and either 465 or 587 for SMTP. Both SMTP ports work; pick whichever your client's defaults prefer.

If your client offers a "no encryption" option, don't use it — we don't accept unencrypted IMAP or SMTP on any port.

Check 5 — ISP, network firewall, or VPN isn't blocking port 587 / 25

Many residential ISPs (especially in the US) block outbound port 25 by default to prevent home-network malware from sending spam. We don't support port 25 for submission anyway, but some legacy clients try it as a fallback before 587 or 465.

Some corporate networks or VPN providers also restrict 587 and 465, particularly for "send from non-corporate domains".

How to tell:

1. From a terminal: telnet smtp.trekmail.net 465 or nc -zv smtp.trekmail.net 465. If the connection opens, the port is reachable. If it hangs or times out, something in your network path is blocking.
2. Try from a different network (mobile hotspot, café Wi-Fi). If it works elsewhere and not on your usual network, the issue is local.
3. Try the other port — 587 if 465 is blocked, or vice versa. Some networks block one but allow the other.

Fix: switch to a working network (rare); ask your IT/ISP to allow outbound 587 to smtp.trekmail.net (217.76.58.218); or use TrekMail's webmail interface as a fallback while you sort out the network.

Check 6 — You haven't hit the IMAP connection limit

Each mailbox has a per-plan limit on concurrent IMAP connections, both per-IP and total. When you hit the cap, the IMAP server rejects new connections with "Maximum connections exceeded" or your client shows a generic "couldn't connect" error.

How you hit the limit without realising:

• One IMAP IDLE-mode client (most modern clients use IDLE) holds one connection per folder it's watching. Watching 20 folders = 20 connections.
• Opening the same mailbox in multiple clients on the same machine multiplies the count.
• Phones syncing while a desktop client is also connected — both clients count.
• An old/stuck connection that didn't get cleaned up by the server's keepalive timeout.

Fix:

• Close clients you're not actively using.
• Reduce the number of folders your client watches (most clients have a "watch this folder for new mail" setting per folder).
• Wait 30 minutes — the server times out idle connections, freeing the slots.
• For chronic over-limit situations on a heavy-use mailbox, upgrade the plan.

Check 7 — You're not on Nano trying to send

Nano accounts have can_send: false. Authentication to SMTP works, but every send attempt gets rejected at the SMTP submission stage. You'll see your email leave the outbox briefly then come back with a "554" or "550" error.

Upgrade to Starter or higher to enable sending. Authentication and receiving (IMAP) work fine on Nano; it's only outbound that's gated.

Check 8 — Your daily or hourly sending limit

If you can authenticate and send some messages but later sends are blocked:

Once a limit is hit, sends queue locally in your client (showing as "trying to send") and retry over the next hour or so. They go through automatically when the rolling window clears.

Check 9 — The mailbox is paused or the domain is unverified

If we paused your mailbox (manual admin action, abuse flag, or unresolved billing), IMAP/SMTP for that specific mailbox stops working with a "user does not exist" or "authentication failed" error. Check the Mailbox detail page in the dashboard — paused mailboxes show a "Paused" badge.

Similarly, if your domain's DNS isn't verified (MX, SPF, DKIM not all green), incoming mail bounces and outgoing may go to spam — though authentication itself usually still works. See Checking DNS Status for the verification flow.

Check 10 — Old saved profile in your client

If you migrated to TrekMail from another provider (Gmail, Microsoft 365, cPanel), your client may still have the old account configured with cached credentials. Delete the old account from your client's accounts list entirely, then re-add as new — don't try to "update settings" on the old profile. Some clients (especially Apple Mail and Outlook) get stuck reusing old DNS or cache info from the previous setup.

Common error messages decoded

Still stuck

Open a ticket from the Support page. Include:

• Your mailbox address (alice@yourcompany.com).
• The exact client (Outlook 365, Apple Mail 16.4, Thunderbird 115…).
• The exact error message your client shows.
• Whether you can reach webmail at https://webmail.trekmail.net with the same credentials (this confirms whether the password is right and the mailbox exists).

We can usually point at a specific server-log line in a few minutes.