If you're running an agency and still manually configuring SMTP for each client account, you're burning hours every week on something that should take minutes.

Here's what I've seen working with outreach teams:

The #1 bottleneck isn't the copy — it's the infrastructure.

Most agencies hit a wall at 3-5 client accounts. After that, managing credentials, rotating providers, and extracting fresh leads from inboxes becomes a full-time job.

The teams that scale past this do three things differently:

1. They centralize credential management. One config file, all accounts. No more spreadsheets of passwords.

2. They use multiple sending providers. Not just SMTP — they route through APIs (SendGrid, Mailgun, etc.) based on deliverability.

3. They extract recipients automatically. Instead of manually building lists, they pull from IMAP inboxes — senders, recipients, even email bodies.

I built Thrly Mail to solve exactly this. It handles multi-account IMAP extraction, 7 API providers, and bulk sending — all from one script.

If you're managing more than 2 client inboxes and want to stop wasting time on email plumbing, check it out.