Please clarify by what you mean by 'system is not seeing my email'? That may be helpful. For example, if you send a message to yourself, does it arrive back? Does this happen to whomever you send messages?

If I send an e-mail from my Thunderbird account, it seems to have been sent as it appears in the "sent" folder. However, it is not received at the address it was sent to. I have tried to send one to a couple of gmail addresses I know well without success, but I can send an e-mail to myself at my Thunderbird account successfully. This has only happened recently in the last week or two, and I have no idea why this is the case. (Apologies for the typo in my original question)