I wonder if you have any information or ideas on the following situation?

Between Jan 23 - 29th various emails went missing. They were successfully sent from Outlook 2007 but never reached the recipient. These were various emails from a range of SendGrid sub-accounts.

On Wednesday approx. 2 weeks later, they all arrived between 6pm & midnight. Most emails around this period were delivered as normal.

What could have happened?

The emails did show up on the SendGrid activity log, until their arrival on Wed. I don't think SendGrid know what to say - and are suggesting a mail queue ? Our Outlook clients connect directly to SendGrid's SMTP servers.

We use BT as our ISP. Could they have queued them?

Any thoughts, however vague will be really appreciated.

Charles