102 thoughts on “Comcast Xfinity Port 25 Blocked, Change to 587 For Outgoing Email (SMTP)

  1. For Gary who asks about the ‘Error’ where the Certificate Cannot Be Verified and the Prompt asks if you want to continue using the Certificate.

    The reason for this error should be that Comcast or the email server that you are using is sending a different Security Certificate than you were receiving before you got this so-called ‘Error’. You should be able to reply Yes or No and get the same results which will be that it should allow you to Send/Receive email messages as you did before. I am an AT&T user and this happened to me a while back and I realized what they were doing and called them to notify them that they were sending out an incorrect Security Certificate. AT&T level one support insisted that this was an Outlook problem and I had to contact Connect Tech and pay to have the problem resolved. It took me 45 minutes for me to get level one to transfer me to level two who instantly knew that the problem was on their end and forwarded my notification to the correct area for resolution.

    What the so-called problem was is that the name on the Security Certificate had been changed from the correct email server name used in the Outlook Email Account configuration. I presumed that the server specified in the Security Certificate was something like a test email server. In any event it had all the same email accounts on this other server so what I did was just to change the server names in my email account to match the Security Certificate server name and everything worked again without this ‘Warning’ message. However, the Security Certificate does not list the outgoing email server name so I had to guess what the new email server’s name would be which wasn’t difficult because I just used their naming conventions and applied it to the incoming server name to determine what the outgoing email server name would be.

    In short this should not be a problem other than a nuisance if the same set of circumstances on the Comcast Security Certificate are the same as what mine were.

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