Why is my email not sending, queued or stuck in the Outbox

Why is my email not sending?#

Start with the smallest test that exists: can you send one message to yourself, from the same account, right now? A yes moves the problem onto the campaign, the list or the tool. A no means the account itself cannot hand mail over, and nothing you do to the email will change that.

1. Is the machine connected at all, and is the account still signed in? Both produce a silent queue.
2. Does one message to one address go? If not, the fault is the account or the connection.
3. Does the same message go to a second address at a different provider? If yes, one destination is refusing you.
4. Does a campaign stop while a single message works? Then it is a limit, a list problem or a tool setting.

That order takes about four minutes and it settles almost every case. The failure people fear, a blocked domain, is only one branch of step three, and it announces itself in the bounce text rather than by silence.

What is the difference between queued, sent and delivered?#

The gap that causes the most wasted work is between sent and delivered. A sending service reports sent when the other server takes the mail, and the other server can then say it was undeliverable an hour later. Amazon SES does exactly this, which is why a report that counts accepted mail as delivered reads wrong the moment a bounce lands.

In this app each address is sorted into one outcome: sent with no failure notice is delivered, and anything the provider came back for is a bounce, so delivered plus bounced equals sent with nothing left over. A number for rows that never left the server at all sits separately, because that is our problem rather than the reader's.

Why is my email stuck in the Outbox?#

An Outbox is a waiting room before the sending server. The usual causes are a connection that is not there, an account whose password or token stopped working, an attachment still uploading, a mail program add-in holding the message, or a desktop app that is set to work offline.

• Check the program is online and not in offline mode, then send one short message with no attachment.
• Sign out and back in on the account, since an expired password produces a queue with no obvious error.
• Send the same message from webmail. If webmail sends and the desktop app does not, the app is the problem.
• Take a big attachment out and see whether the message leaves, which identifies a size limit without guessing.
• On a server rather than a desktop, check anything sitting between the mail and the internet, since Microsoft's own sender guidance tells admins to test outbound port 25 connectivity to the receiving servers.

The message is not lost in any of these. It is waiting to be handed over, which is why nothing about the reader can be concluded from an Outbox entry.

Why is my email not sending in Outlook?#

Work out which Outlook you mean, because the three have different faults. The desktop program queues locally, so the causes above apply. Outlook on the web fails on the account rather than the app. An Exchange work mailbox fails on what the organisation allows, and only an administrator can see that.

Then look at what the failure note says. Microsoft publishes a page of the delivery failure messages its postmaster addresses return, and the code inside the note points at a cause: a mailbox that does not exist, a domain with no mail server, a message too large, a recipient over a limit, or a sending reputation problem that asks you to contact their sender support.

Why is my email not sending from Gmail?#

Gmail fails a send for the account rather than the audience: a sign-in that has dropped, a sent message limit reached for the day, a recipient count over the per-message cap, or a spam-looking shape it refuses to hand over. The number you hit is published by Google for the account type you have, so read your own limit rather than a blog post about somebody else's.

The distinction that saves time is between an account limit and a delivery problem. An account limit stops you writing; a delivery problem means your mail reached Gmail and was sorted somewhere you did not want. The first gives you an on-screen error, the second gives you silence, and why email goes to spam is the other post.

Why is my email not sending attachments?#

Size is the cause almost every time, and the limit is set twice: by the server you send through and by the server receiving. A message that leaves your outbox happily can be refused two hops later, so a large attachment is worth treating as a probable failure rather than a completed send.

• Send the file as a link instead, so the message stays small and each reader chooses whether to fetch it.
• Compress or downscale before attaching, since a photo attachment is nearly always the reason.
• Never mail a list a folder of images, because the size multiplies by every recipient and the refusal comes back per address.
• Check the limit your own provider publishes rather than a figure you read somewhere, since they differ and they move.

A campaign that carries a heavy attachment also carries a delivery risk that has nothing to do with consent: filters weigh structure and payload, and a marketing mail with a file in it is unusual in a way that one with a link is not.

Why is my email not sending or receiving at all?#

Both directions failing is an account or infrastructure fault, not a list fault. The checks are a login test, an inbox quota, the incoming and outgoing server settings, and whether the provider has a known outage. A full mailbox stops incoming mail and is reported by the sender's provider rather than your reader.

If you run your own domain, check the mail routing records exist and point where you think they do. A DNS change on the domain can take mail server settings with it, and nothing in the mail program will look wrong.

Why did a campaign stop halfway?#

A campaign that sends part of a list and stops is nearly always hitting a deliberate brake rather than a fault. Every honest sending tool has brakes, and a large share of them exist to protect a shared address space or to obey the law.

The one to insist on is a reason shown on screen. A send that stops without saying why is the difference between a brake and a black hole, and it is a fair question to ask of any tool you pay.

How do I read a bounce message?#

A failure notice opens with a code, and the first digit is the whole answer. A 5 means stop: the address or domain is refused and repeating it does nothing. A 4 means later: the receiving server is busy, full or unsure, and a retry may succeed.

• Read past the code to the sentence, which usually names the reason a machine gave: user unknown, no mail exchanger, message too large, rejected for policy.
• Compare across providers. The same address accepting at Gmail and refusing at a company domain is an address problem, not a you problem.
• Keep them. A list of 5xx reasons gathered over a month tells you which import produced the dead names.
• Do not treat a 4 as a dead address. It becomes one only after it repeats across sends.

A sending tool that turns these into one line per contact saves you reading XML. Here the failure notes arrive in the report against the campaign, and a hard bounce leaves the mailable set by itself.

How do I know whether the problem is mine or theirs?#

Three tests, in order. Send to a second provider: if it arrives, the first destination is the variable. Send from a second network, since a hosting provider or a corporate firewall can block outbound mail that a home connection would not. Send the same content as plain text with no links and no image: if that arrives and the campaign did not, the shape of the message was the issue.

A single address failing is an address. One whole company domain failing is their filter. Every destination failing at once is your send path, and that is the case where you check records, limits and the tool before you touch the copy.

Why does the reader say nothing arrived and I see sent?#

Because sent means a server accepted it. The likeliest homes for the message are junk, a promotions or updates tab, a corporate filter, an old rule the reader forgot, a full mailbox, or a search that missed it. Ask for the one thing that settles it: have them search the address rather than the subject.

The tool-side fixes are authentication, consent and cadence, in that order. Sender reputation is where the long version of that argument lives, and the CAN-SPAM checklist is what a stranger is legally entitled to find in the mail you send.

How do I stop it happening again?#

• Send a test to two providers before every campaign, and read the header rather than trusting the inbox.
• Keep the mailable set honest, so failures come from addresses rather than from your domain.
• Watch the per-campaign bounce count instead of the total, which is how a new bad source shows itself.
• Set the postal address, the unsubscribe link and the sender name once, correctly, so no send is refused for paperwork.
• Raise sending volume slowly on a new domain, which is what a warm-up schedule is for.

Common questions