Guide
Sending personalised invoices from Outlook
Your accounting software produced ninety PDFs. Attaching each one to its own email by hand is an afternoon, and one slip means a customer reads somebody else's numbers. Here is how to do it from your own mailbox, with a check before anything goes out.
Start from the export, not the inbox
Almost every accounting package — Xero, QuickBooks, Zoho, Tally, Sage — will export an invoice list to CSV or Excel. That export is your merge data. You need three things in it:
- the customer's email address
- the filename of their invoice PDF
- anything you want to mention in the message — name, invoice number, amount, due date
If the export gives you a full path in the filename column, that is fine; only the name at the end is used. What matters is that the name matches the actual file.
Get the PDFs into one folder
Most systems export invoices as a batch of individually named PDFs — INV-1041.pdf
and so on. Put them all in one folder, without subfolders. If your system names them by
customer instead of by number, that is equally fine, as long as the column matches.
Worth doing once: sort the folder by name and compare the count against your spreadsheet rows. A mismatch here is the single most common cause of a row that will not send.
Write the message once
The body is written a single time, with column names standing in for the parts that change. In Tellmerge that looks like:
Subject: Invoice {{Invoice}} from Acme Ltd
Hi {{Name}},
Your invoice {{Invoice}} for {{Amount}} is attached, due {{DueDate}}.
Thanks for your business.
Merge fields belong in the subject as much as the body. "Invoice INV-1041 from Acme Ltd" gets opened; "Your invoice" gets skimmed past, and is harder to find again in six months.
Preview, then send
This is the step worth insisting on. Merge mistakes are not random — if you have mapped the wrong column, it is wrong for every recipient simultaneously. Reading the first three assembled messages, each with its attachment showing, takes ten seconds and catches nearly everything that can go wrong.
A row whose PDF is missing should be held back rather than sent bare. Tellmerge does that and names the row, so you can fix the sheet and resend just that one.
Why send from your own mailbox
An invoice is business correspondence, and it should look like it. Sending through your own Outlook account means the customer sees the address they already recognise, replies reach you directly, a copy files itself in Sent Items, and none of your domain's mail authentication has to change.
Routing invoices through a marketing platform inverts all of that: new SPF and DKIM records to configure, a separate sending reputation, and replies landing somewhere nobody reads. More on how delivery works.
A note on timing
Microsoft limits how fast one mailbox may send — around 30 messages a minute, with a daily ceiling that is generous for a work account and much lower for Outlook.com. A run of ninety invoices is comfortably inside that; it simply takes a couple of minutes rather than finishing instantly. Tellmerge slows to whatever rate Microsoft asks for rather than pushing through, which is what keeps a sending account in good standing.
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