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Set up my essential account: an IMAP account port 25 no ssl. The account as built was SMTP, not IMAP.

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Account creation = other? I'm going to try v102. I loaded v115.4.1 on a new machine - old one dead att. I haven't created an IMAP/port25 combination for some time so I have no idea of when the issue resurfaced. Error message to the effect that the target doesn't accept SMTP. To modify the account I am set to the SMTP editor. It seems to me maybe an 'are you sure?' message could be issued wrt to the port 25 designation, but not correcting a non-existent error ; it's up to the ISP - not us. This used to be an issue; but not since the protocol became an entry. So it seems we are once again overriding the desired protocol based upon the port number. This one of those issues with the ISP filtering out port 25 on output - the ISP insists on the IMAP/port 25.. ... There instructions: OIGP.net & OutreachInternet.com Email Server Settings Server Type: IMAP Username: (enter your full email address) Incoming Mail Server: mail.oigp.net Port: 143 Security: No SSL Authentication: none

Outgoing Mail Server: mail.oigp.net Port: 25 Security: No SSL Authentication method: Requires Normal Password

Some programs may require you to manually configure them in order to get the proper settings.

Account creation = other? I'm going to try v102. I loaded v115.4.1 on a new machine - old one dead att. I haven't created an IMAP/port25 combination for some time so I have no idea of when the issue resurfaced. Error message to the effect that the target doesn't accept SMTP. To modify the account I am set to the SMTP editor. It seems to me maybe an 'are you sure?' message could be issued wrt to the port 25 designation, but not correcting a non-existent error ; it's up to the ISP - not us. This used to be an issue; but not since the protocol became an entry. So it seems we are once again overriding the desired protocol based upon the port number. This one of those issues with the ISP filtering out port 25 on output - the ISP insists on the IMAP/port 25.. ... There instructions: OIGP.net & OutreachInternet.com Email Server Settings Server Type: IMAP Username: (enter your full email address) Incoming Mail Server: mail.oigp.net Port: 143 Security: No SSL Authentication: none Outgoing Mail Server: mail.oigp.net Port: 25 Security: No SSL Authentication method: Requires Normal Password Some programs may require you to manually configure them in order to get the proper settings.

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You will need to post the error message verbatim as the actual message is important to determine context.

Some ISPs simply block port 25 as none of their domestic customers are permitted to use a self hosted mailserver so port 25 is not a requirement and it certainly cuts down on the spam and malware making use of infected PC's to transmit mail on port 25. Blocking port 25 for domestic customers also forces commercial customers to pay for the business product to host their own mail servers.

So is the mail server you are attempting to connect to provided by your ISP and they tell you to connect on port 25? If not who is the ISP?

What is the source of the message? I just edited an SMTP entry in my version of Thundbird 115 to use port 25. It was happy to do so. No message no mess no fuss. The vague error you mention sounds like a server refusing to connect on port 25. Or perhaps some sort of third party software blocking outgoing connections on port 25 (something third party antivirus product do frequently)

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Matt, Thanks, very informative. Could not get anywhere with the 'solved' message button in your email or the response choices it was wrapped in. I think it's SOLVED. As for isp etc I think those questions are answered at the bottom of the original - that page is the entire content of their knowledge base regarding email setup. oigp.net is THE isp and mail server and it seems to require IMAP...outgoing port 25 - no other choices. Roundcube will get me through a silly deadline - been a few years since I used it AND I no longer seem to have 'copies' on the server. Doesn't look like IMAP. I'm comparing results with another Thunderbird which works. I will definitely check out virus checkers [They differ between the systems] etc. Pretty sure it's not Mozilla VPN [which got me around the ISP for everything but email, Thunderbird is the only app in their bypass list for me]. OIGP could not connect with the local bank! Anyway, I have many things to check for this port 25 taboo...oigp kept the 25 when they went from POP!? Guess I wandered (in my eighth decade here) - please redact anything stupid. Richard aka D...