Concurrent SMTP connection limits
Some hosted scenarios may implement SMTP connection limitations, such as a maximum number of concurrent SMTP connections from a single IP address, to prevent abuse of their SMTP service. This will require some configuration changes in MetaDefender Email Gateway Security to prevent delays in email delivery, or worse, the not being delivered and put in Permananent failure.
Known concurrent SMTP connection limits
Below is a list of known SMTP connection limits from providers
|
Provider |
Max concurrent SMTP connections |
Notes |
|
SendGrid |
10 |
See https://sendgrid.com/docs/Classroom/Basics/Email_Infrastructure/recommended_smtp_settings.html |
|
AppRiver |
1 |
By default AppRiver only allows 1 concurrent SMTP connection. AppRiver can adjust this on request. |
Handling in MetaDefender Email Gateway Security
As opposed to MetaDefender Email v3 it is not possible to restrict concurrent SMTP connections in MetaDefender Email Gateway Security v4.
To mitigate this issue MetaDefender Email Gateway Security v4 has a mature retry mechanism that most probably avoids the risk of limited concurrent SMTP connections.