What happens when you exceed the limit
HTTP 429 / plan overage. Sending services enforce their quotas at the API, so the failure is explicit and immediate. The reputation of the domain you send from is a separate matter that the quota does not protect.
Where sender reputation sits on SendGrid
SendGrid has no mailbox to warm. It relays the mail your app or platform hands it. Reputation sits on your sending domain and the IP, and mailbox providers build it from what recipients do with your mail.
IP warmup on dedicated IPs is SendGrid's own automated feature.
Seed lists for SendGrid senders
You pay for SendGrid, the list and the campaign whether anyone reads the mail or not. When Gmail files it in spam, it goes unread, and SendGrid still counts it as delivered.
MailStrike seed lists put real Gmail and Outlook inboxes on your recipient list. You add the seed addresses to your SendGrid send, and each seed inbox:
- opens the email and stays on it
- moves it out of spam or promotions into the inbox
- marks some of it important
Gmail and Outlook read that engagement when they decide where the rest of your mail goes. You also see where the real send landed in Gmail and Outlook: inbox, promotions or spam.
Use them two ways:
- Mixed into a send. The seeds go out with a real campaign and engage with it as it arrives, so the send carries good signals while it goes out.
- Sent to first. The campaign goes to the seeds before your list, so the content and the domain have engagement on record when the real send goes out.
Setup is a CSV of seed addresses you add to your recipient list like any other contacts, and one DNS TXT record. It works the same day, and seed lists are sold on their own.
Trial, free tier and new-account restrictions
100/day. Free and trial tiers exist to test integration, not to run campaigns; the volume above them is a plan decision.
The bulk sender rules are a separate limit
None of the caps above is the line that decides placement. Google's and Yahoo's bulk-sender requirements and Microsoft's 2025 high-volume rules set authentication, spam-rate and unsubscribe conditions that apply well below any sending cap; the sender requirements page has them provider by provider, and the auth checker tests a domain against them.
How SendGrid compares
documented cap per day (log scale); basis differs per provider
Questions about SendGrid sending limits
What is the SendGrid sending limit per day?
No standing free plan (free accounts paused after 60-day transition from 2025-05-27); trial 100 emails/day for 60 days; Essentials from ~50k–100k/month. Recipients per day: plan-based. Source: SendGrid's own documentation, checked 6 Sep 2026 (page dated 2025-05-27).
What happens when you exceed the SendGrid sending limit?
HTTP 429 / plan overage. Above the plan's allowance, sending resumes when the quota or plan allows.
How many recipients per message does SendGrid allow?
1,000 per API request.
How do I increase the SendGrid sending limit?
100/day. Volume above that is plan-based: No standing free plan (free accounts paused after 60-day transition from 2025-05-27); trial 100 emails/day for 60 days; Essentials from ~50k–100k/month.
Is there a SendGrid rate limit per minute or per hour?
API rate limits per endpoint.
Does SendGrid have IP warmup?
On dedicated IPs, yes: SendGrid's own automated IP warmup setting. It is a SendGrid feature, separate from the reputation of the domain you send from.
How do seed lists work with SendGrid?
You add MailStrike's seed addresses to your SendGrid send. Real Gmail and Outlook inboxes open the email, move it out of spam or promotions and mark some of it important, and Gmail and Outlook read that engagement when they place the rest of your mail. Setup is a CSV of seed addresses on your recipient list and one DNS TXT record.