Difficulty with e mail addresses

I use eircom.net. When using advanced or basic version - I put in first letter of contact - a no of versions of same address comes up also some brackets and commas. E mail will not send and will not save to drafts. Sometimes I loose all. Any dvice

Instead of using the "default" versions that are displayed, can you just type in the full email address yourself?

Can do but where you have many contacts it is impossible to remember all.

Copy and paste your e-mail contents into a text file for safe keeping on your computer.

As for your contact list I don't use Eircom.net but make sure your contacts were not uploaded using their e-mail address only.
Each contact should be inserted with their First and Second name as well.

That way as you type the name ( and find out what name the system "prefers" you to type, the optional names offered will reduce down to a few close to your intended name.
In my system - which is Thunderbird, I still get more than the address block can let me see all at once, so I scroll down to the right one.

Its basically the old adage in working with any filing system - you set if up for ease of retrieval: quality in, quality out.
It takes a bit of work and time, but I've found that there is no substitute for doing it.

Saves huge amounts of time in the long run.

Thanks for help