Common email attachment limits

We are looking to send an email campaign fairly soon and are interested in the common limits setup on mail servers. We will be sending HTML based emails with embeded images (so they will be attached).

What number of individual attachments will a mailserver allow and at what total filesize?

Thanks in advance...
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scdavisConnect With a Mentor Commented:
I've admined mail systems for 7 or more years.   Not a lot, but enought that I hope you'll listen to this:

Sending bulk email is dangerous.  If you do it even only once, you may get caught - reported or caught by spamtraps and have your mail server stuffed into (r)BLs like SPEWS, SBL, etc..

If that happens, you'll have to wait - and at last count, I believe the SBL protected over 150 million email addresses.  

Look at (sbl) before you start, please.

*IF* you have *REAL* users for that list, here are my comments about email size:

1)  Keep it really small.  Do that by making one of two assumptions;
1a)  Your reader is html-email capable - then put your graphics on a web server.
1b)  Your reader is NOT-html-email capable - include them.

2)  Once you've figured out which method you're going to use, remember that either way -- there are still a LOT of dial-up users out there.  Anything bigger than 50kB, post-mime encoding (about 35kB pre-encoding?) is going to piss off a LOT of users.  For example, a 2MB email is going to take a 56k dial up user..  HOW LONG to get?  Just don't do it.

..  Like the folks above say, there is no strict rule.  The real rule is:  

Don't send bulk email if you want to be popular.

Find a better business model.

Alf666Connect With a Mentor Commented:
Usually, an email email server has no idea about what an attachment is. So, no attachment size will be checked.
But the global size of your email will be. And this limit is totally up to each server's administrator.

What you might want to do is send HTML emails with references (URLs) to images stored on a web server.
It's usually how things are done.

But I hope you're not going to try and spam the world, are you ?
PsiCopConnect With a Mentor Commented:
First, no one likes spammers. If you don't already have permission to send your target audience E-mail, and you still think you're doing your organization a favor, you're fooling yourselves.

Next, there is no "standard" settings in your area of inquiry. Every mailserver is different, every mailserver software has different defaults, and every postmaster has their own ideas about what should be allowed into the mailsystem.

I personally do not use an HTML-enabled mailreader, and I know plenty of people who block embedded images, and some mailsystems I run limit total message size to 10KB (that's right, 10 KILObytes).

If you want to get more info out, I suggest you drop the HTML E-Mail and silly embedded images. If what you have to say is worthwhile, you don't need all that garbage.
ridConnect With a Mentor Commented:
jkeepiAuthor Commented:
Cheers for all the feedback...

Just to put your minds at rest we are definately not looking to spam anyone!

We have ~1,500 email addresses of customers we wish to contact. The emails we will send them will have a clearly labeled unsubscribe feature so they can opt-out at anytime.
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