Coding email signatures

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arcon

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#255603 20-Aug-2019 10:18

I've just made an html email sig with images & social links etc. This may be a dumb question but with sig images is it best to use remote links or local from the hard drive? Or no difference?

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#2302281 20-Aug-2019 10:47

I use externally hosted images, work good only thing is that some clients will popup with "do you want to load external images blah blah". But all options have trade-offs, I just think this is the cleanest/most compatible. At companies, I like to setup a subdomain like sig.domain.co.nz and just put a static version of HTML sig with placeholder text and a signature image, makes it easy to copy/paste (outlook, gmail) or right-click inspect source to select-all/copy/paste HTML for obscure mail clients. Images live under that subdomain too. Easy thing is that if you want to globally update the logo, you can just update the logo to a santa hat or whatever and because it's external, everyone's sig should get updated for new emails.

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#2302294 20-Aug-2019 10:59

You HAVE to use external images - there's no way for recepients to see the images from your local storage.

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#2302295 20-Aug-2019 11:01

Also, email signatures are a finicky thing. Different email clients will render HTML differently. Outlook (most popular with businesses) uses the old Word HTML renderer. This means you can't use any fance CSS when creating HTML emails.

Also scaling is a problem and images may show in different sizes depending on how the recipients computer/phone is set in terms of scaling. Most clients do a bad job at resizing the images based on the desktop scale.

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SirHumphreyAppleby

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#2302296 20-Aug-2019 11:01

You have a third option, which is to include the image as a data: URL within the HTML. I'm not sure how widely supported this is, but it would prevent the remote content warning, and allow the signature to be created without any particular MIME structure. Some clients can be very picky about inline attachments and your client may not do the 'right' thing. E.g. Some won't display them unless they are within the same multipart/related MIME block as the HTML.

SirHumphreyAppleby

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#2302300 20-Aug-2019 11:06

freitasm:

You HAVE to use external images - there's no way for recepients to see the images from your local storage.

I'm assuming he's referring to local copies attached to the e-mail, referenced by Content-ID.

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#2302302 20-Aug-2019 11:12

Which is a bit of waste of everyone's storage.

Also encoded images aren't cacheable and won't benefit of CDNs, etc.

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bagheera

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#2302307 20-Aug-2019 11:19

Also keep in mind, one of the reasons for email going to the spam folder is links to off-site content, and with Defcon 1 on spam filters now a day, I see a lot of people signatures is the reason for their email going to the spam folder.

arcon

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#2302313 20-Aug-2019 11:27

freitasm:

You HAVE to use external images - there's no way for recepients to see the images from your local storage.

I meant as an inline attachment using the file prefix.

arcon

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#2302318 20-Aug-2019 11:37

bagheera:

Also keep in mind, one of the reasons for email going to the spam folder is links to off-site content, and with Defcon 1 on spam filters now a day, I see a lot of people signatures is the reason for their email going to the spam folder.

That's only a reason with incompetently configured spam filters. Over 90% of the companies I deal with (and there are many) are using graphical sigs, its the norm.

SirHumphreyAppleby

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#2302375 20-Aug-2019 14:02

freitasm: Which is a bit of waste of everyone's storage.

Completely agree. Most of my 3.48GB of daily e-mail backup is images that probably shouldn't have been sent via e-mail in the first place. I send plain text most of the time (although it can screw up formatting on replies), and select that option for communication were available.

I currently receive an e-mail each week where the author includes the same image twice (either side of the title). Their client software isn't smart enough to include it once and reference it twice, so every e-mail ends up being much larger than it needs to be.

arcon:

I meant as an inline attachment using the file prefix.

The file: prefix is basically useless in this situation. It might work for internal mail if by some chance the client software allows it (unlikely), but it has no practical use for Internet mail.

When I refer to inline attachments, I'm referring to attachments with a Content-Disposition header set to inline. The file is attached to the e-mail, but referenced using a Content-ID within HTML.

chewster

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#2302400 20-Aug-2019 14:46

freitasm:

You HAVE to use external images

Or Content-ID
Or Inline Embedding

But yeah from what I've seen external images tend to be more widely compatible and less likely to get caught in spam filters. Good overview of pros/cons here:

https://sendgrid.com/blog/embedding-images-emails-facts/

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#2302407 20-Aug-2019 15:24

SirHumphreyAppleby:

The file: prefix is basically useless in this situation. It might work for internal mail if by some chance the client software allows it (unlikely), but it has no practical use for Internet mail.

When I refer to inline attachments, I'm referring to attachments with a Content-Disposition header set to inline. The file is attached to the e-mail, but referenced using a Content-ID within HTML.

Yep as mentioned this was with an HMTL sig (Thunderbird), so the file prefix does work to a remote gmail account on android. But my test logo (only 350 bytes) done this way loads noticeably slower than a sig remotely stored on wix. That alone is enough to turn me off attachments :/

darylblake

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#2302410 20-Aug-2019 15:37

You want to use external links.

You can even collect meta data from these links if you feel that way inclined.

Shindig

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#2302413 20-Aug-2019 15:42

I use external links stored on Azure blob storage, with a CDN distributing them around the world. In my experience HTML signatures are a massive drain of time, as people have mentioned previously; to get rendered correctly.

The little things make the biggest difference.

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#2302425 20-Aug-2019 16:17

I use data:URI with clumsy old Thunderbird on PC & inline html Bluemail on Android.

That's one of the compelling factors for using Bluemail - a full HTML signature instead of "pardon my brevity" or "sent from my iPhone".

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