SMS vs Email for Invoice Reminders: Which Works Better?

You have two channels for reminding clients to pay. Which one actually works?

The honest answer: both — at different jobs. Here's the breakdown.

Email: the record

Email is where invoices live. It's searchable, attachable, and part of the paper trail. For the initial invoice, email is non-negotiable.

• Open rates: typically 20–40% for business email
• Strength: detail, branding, attachments, archiving
• Weakness: easy to ignore, lands in spam, buried under promotions

SMS: the nudge

SMS is where reminders live. A text message is short, personal and impossible to ignore for long.

• Read rates: 90%+ within minutes
• Strength: speed, attention, feels like a human nudge
• Weakness: limited space, no attachments, more intimate (don't overuse)

The winning combo

Use email for the invoice and SMS for the follow-up:

Invoice by email → SMS reminder before due → SMS on due date → email + SMS when overdue

That's exactly the pattern Invoice Reminder runs: branded email with full details, SMS nudges from your own number at the moments that matter, and a one-tap email resend for any invoice that needs a heavier touch.

When to stick with one channel

• Email only: corporate clients who expect formal communication
• SMS only: repeat small clients who pay on the spot when reminded
• Both: everyone else — and most businesses

The rule of thumb

If a reminder is informational, email it. If it's time-sensitive, text it. Most invoice follow-ups are both — which is why the best systems use both channels without spamming either.