- Help Center
- Advanced
SMTP Server Restrictions
To provide the highest possible level of performance, SocketLabs has specific restrictions when sending messages.
- We recommend opening a maximum of 20 simultaneous SMTP connections
- If you open too many connections you will receive the following error:
421 4.4.5 - Too many connections from your host
- If you open too many connections you will receive the following error:
- We limit messages to a maximum of 500 recipients per message
- We recommend sending 50 messages per SMTP connection
- Messages sizes are limited to 40MB in total size