A small building firm in Uphall rang us one Monday morning in a quiet panic. The office PC on the back desk was still pinging every time a customer replied to a quote, but every one of the owner's outgoing emails had been bouncing since Friday afternoon. He had already sent three invoices he was certain had gone through, two site-visit confirmations that had not, and he was about to drive to Livingston to speak to a plumber he could not reach because his email had quietly stopped sending four days ago and nobody had told him.
It turned out to be a password that his website host had rotated as part of an account security update. The POP3 inbox pulled fine because that part of the client was using a saved application password, and the SMTP outgoing side was still trying the old one and failing silently. The fix was ten minutes once we knew. The three days he had already lost were the hard part. “Receiving but not sending” is one of the sneakier small-business IT faults because mail quietly carries on half-working, and we see at least one of these every month on our business IT support rounds across West Lothian. This is the ordered walk-through we use to find the actual cause.
Why the Receive Side Keeps Working
Email clients talk to two completely separate servers. Incoming mail arrives through either IMAP or POP3, depending on how the mailbox was set up, and outgoing mail is sent through SMTP. On most small-business setups the two live on the same hosting account and share a password, but they are two different connections with their own credentials, their own ports, and their own authentication rules.
That split is why the symptom is so often one-sided. The incoming side will keep delivering as long as the server is up and the saved password still matches, because once the client is logged in it just sits there pulling. The outgoing side has to re-authenticate for every message, through a different port, and will fail the moment any one of a dozen conditions changes. If someone describes mail as “half working”, that is almost always what has happened, and the diagnosis is a matter of walking the SMTP path from the keyboard outwards.
Suspect One: An Expired or Rotated SMTP Password
This is the Uphall case above and it is comfortably the single most common cause we see. Website hosts rotate credentials, Microsoft 365 and Google Workspace both nudge users into app passwords when two-factor is turned on, and employees occasionally reset their mailbox password through a webmail interface without updating the Outlook client on the office PC. In all three cases the saved SMTP password on the desktop goes stale while the saved incoming password sometimes keeps working for days, especially on POP3 setups where the client has already pulled a chunk of mail and does not need to log back in constantly.
The giveaway is an authentication error buried in the client's send/receive log, usually reading “535 Authentication failed” or “SMTP server requires authentication”. Owners rarely spot these because Outlook in particular will show the error briefly then disappear it, leaving the outbox silently stacking up. The fix is to clear the saved password, enter the current one — or generate a fresh app password if the host now requires it — and send a test message. Ten minutes, no onsite visit if the owner is comfortable with us dialling in through a secure remote support session.
Suspect Two: The Website Host Has Moved or Reconfigured
A good number of small Uphall and Broxburn businesses have their email running on the same hosting account as their company website. If the website gets moved to a new provider — a redesign, a cheaper annual plan, a WordPress migration — the mail server details change at the same time, often without the owner realising. The incoming side can appear to keep working for a few days through DNS caching, but outgoing mail goes to an SMTP server that no longer accepts the account.
The tell is a server name in the outgoing settings that does not match the current host, or a server that answers on the old port but refuses the login. If the business's website design and build is handled by a separate agency, the first phone call is usually to them to confirm the new mail server details. If the mail and the site are both managed in-house, we can sort this one in a short remote session or come out on a quick callout. If the business is thinking about a new website at the same time, we can line the mail up with it properly through our website design and build service so this one does not catch anyone out again.
Suspect Three: Antivirus or Firewall Intercepting Outgoing Mail
A long-standing but still-current cause. Several consumer antivirus suites — some that end up on business machines because an owner installed them at home and brought the laptop back in — try to scan outgoing SMTP connections for spam. They sit as a man-in-the-middle on port 587 or 465, and when the real mail server tightens its TLS requirements the antivirus's proxy stops being able to negotiate the connection and silently drops it. Incoming mail is often scanned differently and keeps working. The symptom is the exact one we started with: receive fine, send bounces or times out.
We confirm this by temporarily disabling the mail scanner inside the security suite and sending a test. If outgoing mail then flows, the fault is the mail scanner's TLS proxy. The repair is usually turning the mail scanner off and letting the mail server's own TLS do the job it has always been designed to do. A reputable antivirus is a good thing on an office PC; its outbound SMTP proxy, in 2026, is not.
Suspect Four: An Overloaded or Broken Outbox
Rarer, but it happens enough to be worth checking. If the client has been trying to send a very large message for days — a dozen phone photos of a job attached to one email, say — the stuck message can clog the outbox so that nothing else gets through either. The authentication is fine, the server is fine, but the client is quietly stuck on the first message in the queue and will not move on.
The giveaway is that one specific message is sitting there, often marked with an italic subject line in Outlook, and the number of pending items in the outbox has stayed the same for days. The fix is to open the outbox, delete the oversized message, and either resend it with the photos uploaded to a shared folder instead or compress the attachments. We usually use this moment to talk about a proper file-sharing setup — a nicely-set-up OneDrive-backed workflow prevents a lot of the ten-photo-per-email habit that caused the clog in the first place.
Before You Phone Us: A Three-Minute Owner Check
Two things that are worth trying before paying for a diagnostic, because they occasionally turn a “dead sending” into a “cured by lunchtime”.
First, send a test email from the business's webmail login in a browser, not from the office PC. If that goes, the mail account is healthy and the problem is specifically on the desktop — a credential, a scanner, a stuck outbox. If webmail cannot send either, the fault is on the host and that becomes a conversation with the hosting company, not with us. Second, note down the exact error message the client shows when it tries to send — even if it only appears for a second. “550 relay denied” and “535 authentication failed” look similar from across the room and have completely different fixes. A photo on a phone is enough.
If the inbox has quietly stopped filling too, or the whole PC has slowed down over the same period, the problem may not be email at all. A sluggish machine suddenly developing network issues is a different diagnosis path, and our walk-through of a Currie office whose file sharing dropped out covers how we untangle the two.
When It Needs More Than a Password Reset
If the SMTP settings are correct, webmail sends fine, antivirus is out of the way, and the office PC still refuses to deliver outgoing mail, the fault has moved on from “settings” and into the operating system itself. A corrupted Outlook profile, a damaged mail store, or Windows Firewall rules that have been tampered with by a previous “cleanup” app can all stop sending while leaving the receive path alone. Those are proper bench jobs: we pull the mail store, rebuild the profile, and reset the outbound rules to a known-good set. In the past twelve months we have seen the same pattern after a Windows feature update went sideways, and the Haymarket post about a cracked office install after an update describes the same recovery steps on different software.
If the mapped drive the mail store lives on is itself dropping out, that is a different problem again — the symptom overlaps, and we have written up a shared-drive dropout from another Uphall office that is worth a read if the mail problem started at the same time as files stopped opening cleanly.
Bringing (or Opening) the Office PC From Uphall
If you are in Uphall, Broxburn, Winchburgh, Pumpherston or anywhere else in EH52 and EH53 and the office email has gone one-way, you have two sensible options. For a routine credential or settings fault, we can dial in through a secure remote session and sort it the same morning. For anything more involved — a corrupted profile, a Windows account issue, a firewall rule that needs rebuilt — the PC comes in to the bench and we aim to turn it around on the same day. Our local same-day computer repair service for Uphall has the collection details for the village and the EH52 postcode.
Either way, you will get a plain answer and a quote before any work starts. If it is ten minutes of credential work, that is what we will do and tell you. If the mail store needs rebuilt and the client re-profiled, we will walk you through what that looks like and how long the office PC will be unavailable. No invoice goes to a customer who is still waiting to find out whether their invoices are reaching their customers.
Book a diagnostic online or get in touch and we will take a proper look.
Last updated: 13 October 2026