topic Re: MacMail crashing after sending email in Email

MacMail crashing after sending email

chalkridge — Thu, 12 Mar 2026 15:39:16 GMT

Soon after my migration to Greenby my iMap folders disappeared. To get them back I deleted and re-created my plusnet account in my Mac client. This resolved the folder problem but since then I've had problems sending outbound emails.

Initially the messages (even to myself) just disappeared then the Mac mail client started to crash a few seconds after trying to send.

I again deleted and re-created my plusnet account in my client and sent a number of test messages. For the first 5 messages everything was fine, but for any further messages the client has crashed.

i accept that this might be a client side problem, but it's strange that these problems have only started since migration....no problems prior to that.

Is anyone else seeing similar problems?

for the record I'm running macOS Ventura 13.7.8 on a MacBookAir with an M2 processor. in the absence of other ideas I'll probably upgrade macOS, but that's quite big leap so I'm being cautious.

Re: MacMail crashing after sending email

mavison — Thu, 12 Mar 2026 15:59:54 GMT

@chalkridge

What settings for server name, port, encryption and authentication do you have now?

Are you sure they are what you had previously?

Re: MacMail crashing after sending email

chalkridge — Thu, 12 Mar 2026 16:12:54 GMT

I'm currently running with

Hostname: relay.plus.net

Port: 587

Authentication: Password

Use TLS/SSL checked.

I've tried other settings as recommended in various forum posts but they still didn't allow outbound mail to be sent.

Re: MacMail crashing after sending email

PhilipHeyes — Thu, 12 Mar 2026 16:38:05 GMT

SMTP Port 465 is used with SSL/TLS encryption

OR

SMTP Port 587 is used with STARTTLS encryption

If the email client is still unable to send, try a test send from webmail : webmail.greenby.com

Re: MacMail crashing after sending email

chalkridge — Thu, 12 Mar 2026 17:37:31 GMT

thanks for your suggestions. I'm testing them now.

The client still crashes when using Port 465 with SSL/TLS

For Port 587, the Mac mail client I'm using doesn't appear have an option for STARTTLS. What do you recommend?

I have send emails from Greenby Web mail.....even to hotmail addresses.

Re: MacMail crashing after sending email

chalkridge — Thu, 12 Mar 2026 17:41:41 GMT

Some online instructions say use TLS/SSL with Port 587. I have tried that with Authentication set to password, but the cilent still crashes.

Re: MacMail crashing after sending email

PhilipHeyes — Thu, 12 Mar 2026 18:02:24 GMT

Are you using the correct SMTP server :

https://greenby.com/support/knowledgebase/article/29

Re: MacMail crashing after sending email

jab1 — Thu, 12 Mar 2026 18:17:43 GMT

@PhilipHeyes those ports look horribly outdated/wrong to me.

Re: MacMail crashing after sending email

PhilipHeyes — Thu, 12 Mar 2026 18:47:02 GMT

What can I say ... I did mention this legacy port issue as bad guidance only a few hours ago !

Re: MacMail crashing after sending email

MisterW — Thu, 12 Mar 2026 18:58:54 GMT

@chalkridge is macmail failing when sending the message or when trying to store the message in the sent folder ?

Re: MacMail crashing after sending email

chalkridge — Thu, 12 Mar 2026 19:08:58 GMT

I have tested the settings recommended in the article.

Of the 7 test messages I have sent 3 have succeeded and 4 have crashed the client.

Strangely replies to an existing message don't crash the client.

Re: MacMail crashing after sending email

chalkridge — Thu, 12 Mar 2026 19:12:31 GMT

It's hard to say exactly....the message don't get sent or added to the sent folder. I assume that the send operation is done first so i'd say it's the send that causes the client crash.

Re: MacMail crashing after sending email

MisterW — Thu, 12 Mar 2026 19:18:36 GMT

That's my theory out the window then....

Re: MacMail crashing after sending email

chalkridge — Thu, 12 Mar 2026 20:33:05 GMT

Update:

I have stopped the mail client from crashing by changing the Undo Send Delay to 20 secs.

So now I'm just left with the original problem that outbound emails just disappear......not reaching the recipient nor in the Sent list and no non-delivery notifications in the Inbox or junk.

The Mac Mail Connection Doctor tool shows both connections are

I have trawled the Apple community found a post from 2023 which describes a very similar problem.

https://discussions.apple.com/thread/255154654?login=true&sortBy=rank

The summary of that thread is that the crashes are possibly server side problem that the client doesn't handle it properly when Send Delay is off.

But i'm still no wiser about why outbound emails are failing.

Is there any further logging I can enable to see what's happening?

Re: MacMail crashing after sending email

chalkridge — Thu, 12 Mar 2026 20:50:49 GMT

I managed to use the Connection Doctor logging to track an outbound message.

The final log file entry is:

READ Mar 12 20:44:28.586 [kCFStreamSocketSecurityLevelNone] -- host:relay.plus.net -- port:25 -- socket:0x6000003773c0 -- thread:0x60000396f080
250 0mtPwOm2ukMb10mtQwy1iK mail accepted for delivery

The final line saying "mail accepted for delivery". seems to imply that connection and submission is happening Ok, but the message isn't being handled by the relay.

Anyone disagree with my conclusion?

Re: MacMail crashing after sending email

jab1 — Thu, 12 Mar 2026 20:56:07 GMT

Clutching at straws here, as mail is not one of my specialities, but I'm wondering if the fact that your outgoing port is not the correct one - it should be 587 - has any bearing on this?

Re: MacMail crashing after sending email

PhilipHeyes — Fri, 13 Mar 2026 07:23:14 GMT

-- host:relay.plus.net -- port:25 --

Use of SMTP Port 25 often means encryption is disabled causing the Credentials and message contents to be exposed.

Re: MacMail crashing after sending email

jab1 — Fri, 13 Mar 2026 07:56:13 GMT

It is not the correct port anyway, it is only meant for MTA to MTA transmission.

Re: MacMail crashing after sending email

markhawkin — Fri, 13 Mar 2026 09:28:46 GMT

I think I might go for an operating system upgrade as that will (or strictly should) update Mail.

My guess is that it’s a problem with Mail.

Alternatively try a different Mac mail client.

Re: MacMail crashing after sending email

PhilipHeyes — Fri, 13 Mar 2026 09:49:44 GMT

Is Thunderbird email client an option for you ?