SMTP error sending mail

Hi Ken,

Check with your ISP to see if they may have changed the security requirements for sending mail. For example, last year Verizon changed their security requirements and users had to reset their outbound port to 465 in order to continue sending mail via Verizon. (The default is port 25, which Verizon now blocks.) If this is the case with your ISP, it would explain why you can receive mail but not send.

You can try going to mail preferences>accounts and check that SMTP is not set to none, also un-click use only this server.

It is not your ISP or the settings for the SMTP servers. It is simply Mac Mail.

If you do a search you will find you are not alone. At any give time/point Mac Mail will just stop sending or receiving mail, or both, for no apparent reason.

If you install Any Other mail client you will have no problems.

Deleting and recreating the accounts can also work sometimes.

You are absolutely correct, In Mac Mail.

I have been using computers for over 20 years and have used a total of 5 email clients in those 20 years. Mostly Outlook Express, Outlook, Windows Live Mail, Mac Mail and now on all computers, Mac and PC, Thunderbird. With 4 of them I never had any problem sending and receiving mail, and I never had a problem with Mac mail but I used it for a total of maybe 2 or 3 days before I switched over to Thunderbird on OS X and then got rid of Windows Live Mail on PCs and installed Tbird of those computers. I have never had to Delete an account and recreate it in any of those other programs. Once it was set up and working it continued to work for Years.

Like I said in my post above if you do a search someone someplace is always having problems with Mac Mail sending or receiving Email. Without those users making any changes to the mail program, their email account settings or their system. It just stops.

sanjampet wrote:

Deleting and recreating the accounts can also work sometimes.

I can't comment on Mac Mail because I don't use it ... so I never had a problem with it 😉 ... however ...

The problem as reported by the OP could very definitely be the ISP, and warrants consideration in the diagnostic trail. The example I gave about Verizon was a very real and serious issue for many users who were not aware of the need or reason to change the outgoing port in their account settings. It didn't matter what email client you used ... Mac Mail, TBird, Outlook, Entourage ... if you didn't change your account settings from the default port 25 to the newly required port 465, outgoing mail would simply stop. And it was inexplicable to those who didn't know about, or didn't bother to change, the outgoing SMTP port number.