Delayed Mail Arrival

Has anyone noticed recently that mail seems to be going a little bonkers in that even when I am not sitting all day at my computer I will check my mail at least once every half an hour, and yet hours and hours maybe even the following day after an email(s) was sent to me and received it/they will pop up from nowhere in my mailbox! This is not a good thing as I work from home and depend on receiving my email and many of which are time sensitive at the correct time, not a day later. Even when I manually check my mail nothing new nothing shows. Yet... if I quit and reopen Mail (experimented with this) new mail will pop-up and as said some that had been sent hours before when Check Mail had just told me that there was no new mail???

I would verify permissions in Disk Utility as a first step, given your symptoms, but I would also think that this may be to do with the mail server used by your email account.

Seen this before using an ATT Yahoo account drove me crazy called them (AT&T) by
the following day everything went back to normal.

Thank you Kevriano and OSXX - I did check the verify permissions option Kevriano, and the second thought you had may very well be valid. I have all three of my accounts set up to appear in Mail - AOL, GMail and Yahoo. I will have to pay attention as to which server the missing mail originates from. Might take a while as I rarely use either GMail or Yahoo. All of my contacts email me to the AOL address. If it continues you though I might have to switch to GMail permanently and just let everyone know of the switch bit by bit.
Ta ever so much.