all of a sudden i cannot send emails in mail on my mac. I can send emails using the same smtp settings on my ipad ?

Hello,

Who is your provider, the part after the @ sign?

I would go to easyspace's website and confirm their required "Outgoing Mail Server (SMTP)" settings that you have to enter in Mail>Preferences>Accounts. Often, some actions such as upgrading to Mountain Lion, for instance, corrupt the settings you had in Mail before the upgrade. One possibility.

Hope this helps 🙂

Settings For Most Email Clients Using POP

Email settings differ for Domains/Email accounts set up before and after November 2004. You can check which apply by doing a whois on your domain. If name servers are listed as NS4 and NS5, refer to the Email settings listed in yourServiceCentre account under Email Management > View Configured Mailboxes > Settings. If the domain is listed on NS1 and NS3 name servers settings will follow those included in the screenshots below

The receiving email ports are:

IMAP is port 143

IMAP-SSL is port 993

POP is port 110

POP-SSL is port 995

Outgoing ports are...

SMTP and SMTP-SSL is on ports 25, 587 and 465. Port 587 has to be SSL, and port 465 is enforced TLS-wrapped and is generally used by Outlook users.

But I found this thread interesting...

https://discussions.apple.com/thread/3187763?start=0&tstart=0