1. How many emails can I send per domain per day?
With 10 mailboxes per domain, you can send up to 300-350 emails/day (at 30-35 emails per mailbox). For aggressive sending (50 emails/mailbox), that increases to 500 emails/day per domain—but with increased risk.
2. What are the best warmup configuration settings per mailbox?
To achieve optimal deliverability, we recommend a gradual and consistent warmup process for each mailbox:
Daily warmup volume:
Week 1: 5–10 emails per day
Week 2: 10–15 emails per day
Week 3: Up to 20 emails per day
Reply rate: Maintain warmup replies between 30%–50% to simulate natural engagement
3. Do I need to continue warmup after I start outreach?
Yes. We strongly recommend continuing warmup even after outreach begins. Warmup emails help maintain mailbox health and sender reputation while outreach emails scale gradually. You can run up to 10 warmup emails/day alongside 10–15 outreach emails/day per mailbox. Stopping warmup abruptly can negatively impact deliverability over time.
4. What happens if I exceed the daily sending limit?
Sending more than the recommended volume may result in emails landing in spam or temporary mailbox suspension to protect deliverability.
5. What tools can I use with SkySenders mailboxes?
You can integrate mailboxes with any cold email tool that supports SMTP/IMAP — such as Instantly, Lemlist, Smartlead, Mailrush, Quickmail, and others.
6. Should I use HTML or plain-text emails?
For cold outreach, plain-text emails are preferred. Keep the email short, personalized, and free from spammy formatting or links.
7. Can I track open and reply rates?
Yes, but tracking is done through the cold email platform you connect with SkySenders mailboxes (e.g., Smartlead, Lemlist, Instantly).
