Maximum Attachment Size

[johannes]

A customer came up with the request to be able to send more than the standard 50mb attachment size limit per email. I digged around and found those limits from the big player:

Office 2016/2019: 20mb
Gmail: 25mb
GMX: 50mb
Office365: 25mb (till max 150mb on demand)
.. and info: MIME/Base64 conversion can take up to 30% of message size, so if a 150mb limit is set, the attachment size could be something around 100-130mb in such a case.

Now my question are:

1) are there any technical downsides or other limits, to go for higher limits, as 150mb with exim? (Beside the fact that some receiver cant get the message anymore, because their server wouldnt accept such big messages. Lets assume they do.)

2) Can the sending process from such a big mail eventually pose a disadvantage to other customers, disturbing their mailsending, or can it harm the general sending processes?

3) what limits are you using?


(please @mxroute it would be great to get a stripe from your knowledge here, thanks)

 

[Hostmavi]

Hi Johannes

1. sure you can change the size of massege in /etc/exim.variables.conf
but this is only if you want to send bigger massege size (defaul 50MB)
this is not mean other server will accept big masseges
as you wrote Gmail: 25mb this mean Gmail will accept only emails max 25MB attachment

2. i will not suggest to you sending mails bigger than 50MB
! !bigger files scanning Need more resourses cpu to scanning !!
and will not scaning with defaul setting (like spamassassin).
and mybe other server will not accept big masseges

3. we are using defaul settig (50MB)
25MB-30MB attachment really a reasonable limit.


your customer should Compress files like .zip
For larger files, use file-sharing services or cloud storage platforms like Google Drive, Dropbox, or OneDrive

last Thing creating Password Protected Directories
whit username and Password upload bigger attachment ther.
each user can Login link whit his username and Password download the attachments

 

[johannes]

1. sure you can change the size of massege in /etc/exim.variables.conf
but this is only if you want to send bigger massege size (defaul 50MB)
this is not mean other server will accept big masseges
as you wrote Gmail: 25mb this mean Gmail will accept only emails max 25MB attachment

Yes, I did it in exim.variables.conf.custom. Yes, clear, the receiver must also accept those limits.

! !bigger files scanning Need more resourses cpu to scanning !!
and will not scaning with defaul setting (like spamassassin).

Good point, thank you, I will check SA.

your customer should Compress files like .zip
For larger files, use file-sharing services or cloud storage platforms like Google Drive, Dropbox, or OneDrive

yupp, I told him to do this, or use ftp on own webspace.


I take CPU-peaks for SA scanning on the list - thank you for this!!

Beside that, whats about other process/timeout- limits, are there any? Which ones? Any other technical barrieres?

 

[Hostmavi]

I know only this 2 Setting in /etc/exim.variables.conf

if server loads bigger then this Setting Queue will not deliverd .

deliver_queue_load_max=10.0 (defaul 10.0)

same Setting for receive mails

queue_only_load= 20.0 (queue incoming if load high)

pls read also exim doc.

 

[mhsolutions]

I think You can increase size from php.ini (php1). But some email (your customer) can not receive it because it > 25MB.
In MS mail, if it is larger than 25MB, it will be up to onedrive and insert a link to email. It is not attach file

 

[Richard G]

1.) I wouldn't go any further than the big guys like MS and GMail. And if they use 25 MB then nice that GMX is using 50 MB but remember that is already very big. So it could really result in several mail accounts not be able to receive the mail and maybe some old accounts faster getting their mailbox full.

If it's only for 1 customer I wouldn't even think about it and tell him that is not market-conform and he can use very big size by free tools like WeTransfer to get this to others.

2.) Already answered bij @Hostmavi

3.) I use the DA defaults, in 2004 this was already 50 MB which is way more than enough. Because as you can see, Gmail won't accept it already and some others. I didn't look up if the default is still 50 MB.