Email arrival delays can occur due to any number of mechanisms, from misconfigured email servers to spam and virus protection systems (like greylisting) that are intended to delay messages here and there so as to best protect you from spam.
Messages you've sent to someone else
If the delays are occurring after you've sent a message out, such that your recipient is reporting that it took longer than 5-10 minutes to receive your message, you will need to have them obtain the message headers (click here to learn how), save them in a text file, then send them to you.
Open a ticket with the file containing the headers attached and we'll be able to determine exactly what happened with the message and where it was delayed. If the delay occurs in an external server, then we may not be able to indicate why a message is delayed; that will need to be asked of the admins that run the server that caused the delay.
Messages someone else has sent to you
If you are the recipient of the messages that have been delayed, first try the steps here to disable greylisting.
If that doesn't resolve the problem, then you'll want to follow the directions described here to obtain the message headers. Save them to a text file and attach them to a support ticket to send them to us for diagnostics.
