MergelineIs mail merge safe to use?
Updated October 29, 2026
Mail merge itself is just sending separate emails, so it is safe when done with care. The risks sit in three places: your account (sending too much, too fast), your data (tools that store your lists and emails on their servers), and the tool (what access it has to your Gmail). Google’s built-in mail merge avoids the third-party part entirely, but only on some plans.
Risk 1: your account
Bulk sends from a new account or to a bad list can get an account suspended. Pace your sends and clean your list. See suspension after a mail merge.
Risk 2: your data
Many tools copy campaign data to their servers. Mailmeteor keeps recipient addresses and merge fields for 180 days. GMass stores recipient addresses and passes email content through its server; its privacy page says list data may be shared with ad platforms such as Google.
Risk 3: the tool’s access
Google classes Gmail access that reads or changes mail as “restricted”, and apps that store that data on servers must go through a security assessment. Even trusted extensions can be hijacked: in December 2024, attackers pushed a malicious update to Cyberhaven’s Chrome extension.
How the options compare
| Option | Third party sees your data? |
|---|---|
| Gmail built-in mail merge | No, it is Google’s own feature |
| Sheets add-ons | Usually some, check their privacy page |
| Mergeline | No. Lists and results stay in your browser |
Mergeline has no server that receives your lists or emails. Its only server handles license keys for Pro. More on the security page.
Quick checklist
- Read the permission screen before you click Allow.
- Read the tool’s privacy page: what does it store, and for how long?
- Start slow on new accounts and clean your list.
Keep extensions few
Every extension you install can update itself, which is how the Cyberhaven attack spread. Keep only the extensions you use, and remove the rest.
Read the full guide: How to mail merge in Gmail
Related answers
Sources
- Mailmeteor privacy docs
- GMass: what data our server stores
- Google: Gmail API scopes
- TechCrunch: Cyberhaven’s Chrome extension hacked
Facts checked October 29, 2026. Google and other vendors change their limits and prices, so check the source before you rely on a number.
Mergeline does this from your own Gmail. Free for 60 emails a day with merge tags and no branding. Pro is $12 a month or $99 a year for follow-ups, scheduling and attachments.