Definition
💡 When performing email throttling, you’re strategically limiting the number of emails you send for a certain time period. Sending emails in batches helps keep them from being marked as spam.
Example
When you send an email that exceeds your ESP’s acceptable threshold, it rejects your email. This leads to soft bounces, where the email is directed to the recipient’s mail server but doesn’t get through their inbox.
When should you throttle emails?
The normal throttling size is between 500 and 10,000 emails. This applies to each throttling period. Note that there are several points where you could throttle emails:
- When you’re sending emails to more than 250 contacts.
- When you’re sending emails from a new IP address.
- When sending messages to a new list.
- When you’re sending emails too fast to avoid ISPs flagging your messages as spam.
What does it mean when a message is throttling?
When your email service provider (ESP) sees a sharp rise in sending volume, they may flag this as a high-risk signal. This likely indicates automated activity or that your account may be compromised. Your ESP may automatically classify your email as spam or block outbound emails.
Your ESP limits the volume of emails it can accept. It then prevents subsequent delivery attempts, leading to soft email bounces. These soft bounces are temporary, unlike hard bounces.
What is SMTP throttling?
SMTP throttling refers to the process of limiting the rate at which your emails are sent via an SMTP server. It’s important if you’re:
- Sending a large volume of emails too quickly – SMTP throttling prevents your SMTP server from being overwhelmed, which can lead to performance issues.
- Exceeding the sending limits set by your ESP – SMTP throttling can prevent your emails from being blocked or marked as spam.
SMTP throttling works by setting limits on parameters like the number of emails sent for a specific period or the number of SMTP connections. SMTP throttling rates are also adjusted based on factors like your sending reputation and the ISP policies of your recipients.
When performing STMP throttling, make sure to:
- Follow a consistent send rate.
- Gradually increase sending limits.
- Clean your email lists.
What does “send throttled” mean?
"Send throttled" means intentionally limiting the volume of outbound rates. This is useful if you’re aiming to have a consistent sending rate.
