A mysterious problem: when I reply to an email, everything seems ok. My reply appears in the sent folder, and the email header looks correct. However, the email is never received. Normal sending and receiving works fine.
What could be the problem and how do I solve this? Let me know if I need to provide more info. I hope someone has a clue! 
Is this happening with all emails you reply to, or just some?
Yes it happens with all the emails I reply to. Replies don’t end up in the receivers spam box either.
Was wondering if it could it be a problem with the external DNS? I use a standard emailadress from my provider, but mail & reply everyone with my personal alias emailadress, which is on a different domain… Perhaps there is a misconfiguration with the alias/standardadress and the reply-to?Â
I would suggest that you logon to the web interface for the address in your smtp settings in eM Client, and see if the emails are in your sent folder.
None of my emails (sent or received) show up in the webmail when i use an emailclient. Thats for eMclient but also outlook which i used before.
Who is your email provider?
And the replies you sent through Outlook were being delivered OK?
It’s Telfort, and yes through Outlook everything was ok!
Are you using the Alias feature in eM Client?
yes, here are my settings:
pop3.telfort.nl poort 110
smtp.telfort.nl poort 587
accountname: [w******@telfort.nl](mailto:w ****** @telfort.nl)
user: My Name
e-mail **************@wolmail.nl
alias: [w******@telfort.nl](mailto:w ****** @telfort.nl)
I am confused by your answer. If your account setup is smtp.telfont.nl, then the alias must be the wolmail.nl address.
Your Alias config should look like this:
Yes oops that didnt make much sense indeed, i switched them around when looking for a solution.
With email and alias switched now, I cán reply to emails if I send the 1st email. But when somebody emails me first, and then I reply, it is not delivered.
Are the replies to emails you send first coming to your telfort.nl address, and when somebody emails you first the messages are going to your wolmail.nl address?
Hmmm yes i think so! In the first case, the email header says from @telfort.nl and when somebody mails me first my replies say from @wolmail.nl
I know that GMail has this facility, but did you make any changes to settings on telfort.nl web interface to enable aliases?
Been looking for it, but can only set @telfort.nl aliasses 
I don’t know what to say Mirjam. I though if you had maybe setup an alias on your telfort server, that it might have been causing some problem. But that is not the case.
What I see is that when you are sending emails using the alias feature in eM Client they are not arriving at their destination. You said that you don’t have a sent items folder in your webmail, so there is no way to see if they have reached the server.
Your best bet is to contact telfort.nl and tell them that emails you send are not reaching the recipient despite a copy being in your sent items folder on your PC.