If you've landed here, you're probably trying to work out whether Mailsuite (the Gmail extension formerly called Mailtrack) can actually handle the bulk email you need to send. Quick disclosure: we built Sendflo, so weigh that accordingly. We've tried to be honest here, which means we'll tell you the parts where Mailsuite is the right call too.
Mailsuite started as Mailtrack, the read-receipt tool you've probably seen the ads for. Over the years they've layered in mail merge, PDF tracking, and eSignatures. It still lives entirely inside Gmail as a browser extension, and that's both its strength and its ceiling.
Because it piggybacks on your Gmail account, every message goes out looking like a normal email from you. That's useful for individual sales emails. It becomes a problem when you want to send a newsletter to 25,000 people.
Sendflo (sendflo.io) is a proper bulk email platform. Not a plugin, not a layer on top of something else. You log into app.sendflo.io, build a campaign in a visual editor, upload your contacts, and Sendflo handles delivery through its own infrastructure with automatic retries. We've had 100% uptime since launch, which isn't a claim we make lightly.
| Feature | Mailsuite | Sendflo |
|---|---|---|
| Sending infrastructure | Your Gmail account (~2,000/day Workspace limit) | Dedicated queue with retries, 100% uptime |
| Email builder | Gmail compose window only | Drag-and-drop visual builder, preheader support |
| AI features | None | AI writer, subject lines, contact scoring, send-time |
| Bounce handling | Manual: you clean the list yourself | Automatic suppression on future sends |
| Unsubscribe compliance | No documented RFC 8058 / List-Unsubscribe header | Built-in, as required by Gmail & Yahoo for bulk senders |
| Custom sending domain | No; sends from your Gmail address | Yes, on Growth plan and above |
| Segments | Google Sheets / Gmail contacts only | Native tags and segment filters |
| Per-campaign recipient cap | 10,000 recipients, 1,000 simultaneous sends | No per-campaign ceiling within your plan |
| REST API | No public API; Zapier only on Advanced | Full REST API with bearer token auth (Pro plan) |
| Pricing model | Per seat ($9.99/user/mo on Advanced) | Flat rate per workspace, any team size |
| Mobile app | iOS and Android | Web app (mobile-responsive), no native app yet |
| 1:1 read receipts | Real-time, per recipient | Campaign-level open tracking |
| PDF tracking / eSignatures | Yes | Not available |
Mailsuite charges per user per month. Note that mail merge is only on the Advanced tier:
A 10-person team on Advanced is $99.90/month. You also still can't send to more than 10,000 recipients in a single campaign, even at that price.
Sendflo is a flat rate per workspace. Team size doesn't change the price:
Mailsuite Advanced and Sendflo Pro both allow 60,000 emails a month. Mailsuite costs $99.90 for 10 users. Sendflo is $60 regardless. You can also top up credits on Sendflo without changing your plan.
This is the core issue. Gmail caps sending at around 2,000 messages per day on Workspace. In practice you'll hit friction earlier than that on newer accounts or when Google's filters get suspicious. Mailsuite can't escape this because it sends through your Gmail account. A 30,000-contact newsletter simply isn't possible. Sendflo runs its own sending infrastructure with a queued, retry-backed delivery system. There's no Gmail ceiling to bump against.
Type a prompt like "promotional email for our summer sale, casual tone" and Sendflo's AI writes the campaign. The subject line tool gives you five options to pick from instead of agonising over one. Contact scoring looks at engagement history and flags each contact as hot, warm, or cold. There's also a send-time recommendation that figures out when your list is most likely to open. None of this exists in Mailsuite.
Since February 2024, Gmail and Yahoo require anyone sending bulk email to include a proper List-Unsubscribe header with one-click opt-out. Sendflo adds this automatically on every campaign. Mailsuite doesn't appear to support it. If you're sending high volumes through Mailsuite right now, you may already be getting filtered into spam.
If you're sending bulk email without a List-Unsubscribe header, Gmail may be routing your messages to spam. Google enforced this from February 2024 for anyone sending over 5,000 messages a day.
Sendflo lets you send from hello@yourcompany.com with SPF and DKIM set up properly. When you're sending to large lists, that matters for both deliverability and how recipients perceive the email. Mailsuite sends from whatever Gmail address you're logged into.
Ten people on Mailsuite Advanced costs $99.90 a month. Twenty people is close to $200. Sendflo is one flat price for the whole workspace. Add teammates without watching the bill climb.
Use Mailsuite if you're a sales rep sending personalised 1:1 emails and you live inside Gmail. The per-recipient read receipts and PDF tracking are good. Just don't try to use it as a marketing platform. It'll fight you the whole way.
Use Sendflo if you're sending to any list of real size, you want a proper email builder instead of the Gmail compose window, bounce handling and compliance need to be automatic rather than manual, or your team needs shared access without paying per person.
These two tools aren't really competing. Mailsuite is a Gmail add-on for individual sales reps. Sendflo is a marketing platform for businesses that need to send at scale.
If Gmail's limits have started biting, if you're hand-cleaning bounce lists, wondering why campaigns are landing in spam, or you've realised a $100/month 10-seat plan still won't let you reach more than 10,000 people at once, you've outgrown what Mailsuite can do.
300 emails free, no credit card. Build your first campaign in the visual editor and let the AI write your subject lines.
Get started free →Is Mailsuite good for bulk email marketing?
Not really. Mailsuite is built for 1:1 outreach and small mail merges inside Gmail. Campaigns are capped at 10,000 recipients, and all sends go through your Gmail account, which has its own daily limits. If you're sending marketing campaigns to any meaningful list size, you'll hit walls quickly.
What's the main difference between Mailsuite and Sendflo?
Mailsuite is a Gmail add-on. It's great for sales reps who want to track individual emails and send small mail merges without leaving their inbox. Sendflo is a standalone platform with its own sending infrastructure, a visual email builder, AI writing tools, automatic bounce suppression, and bulk-sender compliance built in. They're solving different problems.
Does Mailsuite support a custom sending domain?
No. Everything goes out from your Gmail or Workspace address. Sendflo's Growth plan and above let you send from your own domain with proper SPF/DKIM, which matters both for deliverability and for how professional your emails look.
Does Sendflo have a free plan?
Yes. You get 300 emails to try the platform with no credit card needed. Paid plans start at $12/month for 10,000 emails, and that tier includes all the AI features: writer, subject line generator, contact scoring, send-time recommendations.
Can I use Sendflo if I'm not in India?
Yes, Sendflo works for businesses everywhere. International users pay in USD via Dodo Payments; Indian users can pay in INR via PayU.