To process a client's vendor invoices from an email inbox without losing or double-counting any, route every bill to one dedicated address, work the inbox in a fixed weekly batch, and move each invoice into a dated client folder before anyone keys it. Sort out statements, quotes and reminders first, and match vendor names against an alias list.
Setting up one inbox for a client's vendor invoices
A dedicated invoice inbox is one email address that receives nothing but a client's bills, such as an accounts payable address on the client's domain. Vendors send to it, the client forwards stray invoices to it, and the firm reads from it. One address replaces the owner's personal mailbox, the office manager's mailbox and the general contact address.
The address can belong to the client or to the firm. If it sits on the client's domain, the client keeps control of the mailbox and the firm gets delegated access or a forwarded copy. If it sits on the firm's side, the firm controls retention and access but depends on the client to update every vendor. Either way, decide who owns the mailbox before vendors are told about it.
Forwarding rules from the old mailboxes
Invoices will keep arriving at old addresses for months. A forwarding rule in each old mailbox catches them.
In Gmail, Google's help page on automatically forwarding Gmail messages to another account explains that forwarding sends all new mail except spam by default. To forward only some messages, the same page says to turn off automatic forwarding and create a filter with the Forward it action. Google's page on creating Gmail filters adds that a forwarding filter affects only new messages, so older invoices still have to be moved by hand. Google's list of Gmail search operators includes has:attachment, filename:pdf, from: and subject:, which combine into a filter such as has:attachment filename:pdf subject:invoice.
In Outlook, Microsoft's guide to managing email messages by using rules in Outlook shows how to create a rule from a message or from Settings > Mail > Rules, with a condition such as the sender or words in the subject. The same page notes a difference on Outlook.com: a forwarded message shows it came from you, while a redirected message keeps the original sender on the From line. Redirecting keeps the vendor's address visible, which helps with vendor matching later. The page also says new Outlook for Windows does not support rules for third-party accounts such as Gmail, Yahoo and iCloud.
What to tell vendors
Send each vendor one short notice: the new address, the date it takes effect, and a request to attach the invoice as a PDF instead of linking to it. Ask vendors who bill through a portal whether the portal can email the PDF. Keep a list of which vendors confirmed, and follow up with the rest after their next bill arrives at an old address.
How to process 200 vendor invoices a month from one inbox?
Processing 200 vendor invoices a month from one inbox works best as a weekly batch of about 50, done on the same day each week by the same person. Each batch runs the same steps in order: sort, save, rename, check for duplicates, hand off. Batching empties the inbox weekly and makes a missed week obvious.
A missed week is the routine's main risk. If a batch is skipped, run the next one in two passes: first the older week, then the current one, so files land in the right month's folder. Check the month's folder count against the email count before closing the month. A shortfall usually means a portal invoice that was never downloaded or an attachment saved to the wrong client.
The weekly inbox routine
The routine below is an example for one client, with fictional folder names. Adjust the day and folders to suit the firm.
- Open the inbox on the set day, for example every Monday morning, and filter to unread messages since the last batch.
- Sort out non-invoices first. Move statements, quotes, payment confirmations and reminders into their own folders (each has its own wording, such as "statement", "quote", "paid" or "overdue").
- Save every invoice attachment to the client's folder for the month, such as "Example Client / 2026-10 / Invoices".
- Rename each file as period, vendor and invoice number, for example "2026-10_harbor-office-supply_20931.pdf", using the vendor's name from the alias list.
- Check for duplicates by sorting the folder by name. Two files with the same vendor and invoice number are the same bill until proven otherwise.
- Download portal invoices for any email that held a link instead of an attachment.
- Label or move each processed email to a "Done" folder, so the inbox shows only what is new.
- Hand the folder off for entry, approval or export, and note the count of invoices in the batch.
Planning the time for each step
Time the routine on your own inbox for two or three weeks before planning staff hours. Record minutes per step and invoices per batch. Then multiply. As an example only: if your timing showed two minutes per invoice to save, rename and check, a 50-invoice batch would need about 100 minutes, plus time for sorting and portal downloads. The figures will differ by client, vendor mix and how many invoices arrive as scans. Keying the data and approving bills come after this routine and are planned separately.
What happens to each invoice after it leaves the inbox, from coding to payment, is the subject of the post on the vendor invoice processing steps in an accounts payable workflow.
Which emails in a vendor invoice inbox are not invoices?
A vendor invoice inbox fills with emails that look like invoices and are not. Account statements, quotes and estimates, payment confirmations and receipts, and overdue reminders all carry vendor names, amounts and often a PDF. Treating any of them as a new bill adds an expense or a payable that does not exist.
Each type has a tell:
- Statements list several invoices, often with an opening and closing balance and the word "statement" in the title. A statement is a summary of bills already sent, not a new bill.
- Quotes and estimates carry words such as "quote", "estimate" or "proposal", a validity date, and no invoice number. Nothing is owed yet.
- Payment confirmations and receipts say "paid", "payment received" or "thank you for your payment". They are proof of payment for an invoice already on file.
- Reminders say "overdue", "past due" or "friendly reminder" and usually reattach the original invoice. The attachment is a second copy of a bill already in the folder.
- Credit memos reduce what is owed. They are real documents that belong with the invoices, but with a negative amount.
Reminders are the main source of duplicates in an inbox, because they carry the full invoice again. The same bill forwarded twice, or sent once as a photo and once as a PDF, is covered in the post on which invoice fields identify a duplicate invoice. For duplicates across a whole client folder, not only invoices, see the post on duplicate document detection.
Vendor name matching across invoices in the inbox
Vendor name matching means recognizing that differently written names on invoices belong to one vendor. The same supplier can appear as its trading name on the invoice, its legal name on the remittance details and a shortened name in the email sender field. Without matching, one vendor's bills are split across three names and totals per vendor are wrong.
Names drift for ordinary reasons. A company adds or drops "LLC" or "Inc.". A billing system truncates long names. An email comes from a person at the vendor rather than the company. A vendor is bought by another company and its invoices change name partway through the year.
A sample vendor alias table
An alias table maps every spelling seen to one standard name. The example below uses a fictional vendor.
| Spelling seen | Where it appeared | Standard vendor name |
|---|---|---|
| Harbor Office Supply LLC | Invoice header | Harbor Office Supply |
| HARBOR OFFICE SUP | Email sender name | Harbor Office Supply |
| Harbor Office Supplies Inc. | Remittance address | Harbor Office Supply |
Keep the table next to the client's folder and use the standard name in every file name and spreadsheet row. When a new spelling appears, check something sturdier than the name before adding it: the vendor's remittance address, its account number for the client, or its tax ID if the invoice prints one. A new spelling with a new bank account is not an alias to add without asking; it is a change to confirm with the client.
An acquired vendor needs a decision as well as an alias. If Harbor Office Supply is bought by a fictional Example Office Group and its invoices start arriving under the new name, decide with the client whether the new name becomes the standard name from that date or the old name stays until year-end. Record the date in the alias table either way, so a per-vendor total for the year can still be traced to every invoice behind it.
Vendor invoice emails with portal links instead of attachments
Some vendor invoice emails carry a link to a vendor portal instead of a PDF attachment. The email says an invoice is ready and asks the reader to sign in to view or pay it. These invoices never reach the client folder unless someone downloads them, so they are the easiest bills to miss in an inbox routine.
Handle them in a fixed step of the weekly routine, not as they arrive. Keep a list of which vendors bill this way, who holds the portal login, and whether the portal allows a PDF download. Save the downloaded PDF to the same folder and name it like any other invoice.
Ask each portal vendor whether the portal can email the PDF itself. If it can, switching that on removes the download step for that vendor. Where it cannot, confirm the portal login belongs to the client and not to one employee, so access does not disappear when that person leaves.
Be careful with links in invoice emails generally. An email that looks like a known vendor's invoice but links to an unfamiliar site, or asks for new payment details, should be checked with the vendor by phone before anyone clicks or pays.
Inbox intake is one of the steps software can share. Which accounts payable steps can be handed to software, and which stay with a person, is covered in accounts payable automation. With Schema CPA, invoices saved from the inbox go to the client's upload link, where each one is read and a reminder email that reattaches a bill already on file is flagged as a duplicate; the Schema CPA workflow shows the steps.