If your clients aren't receiving emails sent through Fergus, there are a few common reasons this can happen and steps you can take to fix it.
Common Reasons Emails Fail to Deliver
Spam filters — Emails may be flagged based on the sender's address or the content of the email. Words like "free," "guarantee," or "winner" in your subject or body can trigger filters.
Gmail or Outlook connection issues — If you're connected via OAuth and the connection drops, emails may silently fail to send.
Client accidentally unsubscribed — A client may have clicked the unsubscribe link in a previous email, blocking all future emails.
Email size too large — The total size of your email and attachments must be under 20MB.
SMTP configuration errors — Incorrect SMTP settings can prevent emails from being sent.
How Fergus Sends Emails
By default, Fergus sends all your invoices and other emails from no-reply@mail.fergus.com. Since we send a high volume of emails daily on behalf of all our customers, email hosts recognise this address as trustworthy — making it the most reliable sending option.
If you're using SMTP or a connected Gmail/Outlook account, deliverability may be lower and will require more troubleshooting when issues arise.
💡 For a full step-by-step troubleshooting guide — including how to check error details in Notes & History, reconnect Gmail or Outlook, fix unsubscribed clients, and resolve spam filtering — see the article below.
Quick Tips to Improve Deliverability
Use the Fergus default email service where possible — it has the highest deliverability
Avoid spam trigger words in your subject or body — "free," "guaranteed," "winner," "earn"
Keep links simple — use plain URLs like www.example.com instead of hyperlinked text
Attach images rather than embedding them — embedded images often trigger spam filters
Check Notes & History after sending — failed emails will show a red "Email failed to send." banner with an Error Details link
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