Emails not being received

I've been having a problem with my emails not being received. It seems to have arisen since the beginning of this month (although difficult to be precise) and it also seems to be arising mainly in relation to emails I'm sending to Portugal.

Some of these emails are being sent in response to people who have emailed me, which seems pretty strange. Has anyone else had this kind of problem and did you discover a solution?

Regards
Homer

Have you checked the security settings /your anti-virus software on your computer. Nortons / Symantec have the problem of blocking e-mails for some unknown reason.

Has the recipient checked if their junk filter has decided to block all emailed from your address and they are sitting in their junkbox ?

Thanks for the replies.

I use Kaspersky for internet security and I haven't changed any settings. Anyway, the problem seems to be only with a handful of recipients (as far as I can tell, 2 in Ireland and 3 in Portugal).

I've sent all the recipients emails from my wife's email address and have asked them to check their junk mail folders and add me to their safe senders list. The one I'm most concerned about is the company that looks after my apartment in Portugal and I've had several discussions with them about adding me to their safe senders list, but nothing seems to have worked.

I've also spoken to my ISP, but I'm using an old email address from my previous ISP (I moved about four months ago) and they told me I'd have to talk to my old ISP about it. I'm planning to do that this evening.

Thanks again

Homer