How many concurrent connections / threads can I use?

Concurrent connections are normally only required when sending very large volumes of email but we do provide the ability to use up to 5 concurrent connections to our service per IP address.

Most normal email programs (Outlook, Entourage etc.) will only use a single connection or 'thread' when sending email to our servers and for these no changes are required.

If you are using mailing list software to send a larger volume of email through our servers there may be a performance benefit by configuring your mailing list program to use multiple connections to our servers.

When sending email to our servers various details have to be checked before the message is accepted which can cause very minor but unavoidable delays, these millisecond delays are not noticeable for normal email programs - however, for mailing list software trying to deliver a large volume of email quickly they can add up.

To resolve this we allow a maximum of 5 concurrent connections per account (or per IP address) - so you can configure your mailing list software to use between 1 and (a maximum of) 5 threads / concurrent connections to our SMTP servers, trying to use more than this may lead to emails being lost and / or having your account suspended.

If you have any questions please contact us.